# South Bend 9 Compound Condition & "weld up" fixes?



## graham-xrf (Feb 28, 2021)

Well - maybe "restoration" is the wrong word!
I have taken it apart with a couple of things in mind. One is to try and repair the broken-off bit of the T-Nut slot. The other is to perhaps do something about the backlash. As mentioned in another recent thread, simply securing the Acme nut with it's grub screw near halves the backlash from 0.022 to about 0.012, and even just this is enough to get it working again well enough to set doing a bigger graduated dial modification for itself, of which there are several YouTube videos that look interesting.

*"Warts & All"*
We know you like pictures, and on this, I need advice. This is the very same compound casting that I posted about from last October where I got excellent suggestions from @Nutfarmer , @matthewsx , @Superburban , @tq60 , @SLK001 , @Gaffer , and some amazing pics from @Ulma Doctor. After considering the approach of cutting away the broken lip entirely, and replacing with a with a bolt-on, versus attempting to weld it up, I have decided to attempt the weld, even though my weld experience is limited to welding up a trailer frame with a cheap buzz-box, long ago. This time, I have a better welder.

So here we go with a condition evaluation, with the paint stripped, and a minimal clean-up.



The strange brown color is as it was under the paint. Is that a kind of rust? I wire-brushed the break. Here is where we come to the first question(s).
Please forgive if I hesitate on these details. I have never done this before, and these are the things I think. It goes without sayinig that in the end, it gets a new paint job!

1. Before the weld, should I grind or cut on the break surface before welding? Maybe one of the little tools with my Dremel.

2. I learn that things go much better if the whole casting is pre-heated to about 300C-400C, and care taken to cool slowly. If one is grinding the break clean, is that done while it is hot?

3. I have the choice of two kinds of welding rod that would leave a repair that can be machined, or filed. Both are recommended for repairs to "cast iron", although this metal is maybe cast "semi-steel". One is 99% nickel. The other type is called ENiFe-C 55%Ni, which I understand is used for welding to cast iron, and between dissimilar metals onto cast iron. It seems to have a graphite-based coating on the rod. I will go with whatever you folk recommend.

4. How are the welds laid in? Where does one start? Is there a planned strategy? Are they "peened"? Can you overdo things, and end up work-hardening with the slag hammer?

5. For slow cooling, I am thinking a mineral wool lined box with insulated lid, filled with sandbox sand. Does the sand need to also be hot when the job is put into it?

6. Will the whole thing be "distorted" after all this, and need other treatment to the surfaces?

*The Compound Condition*
There is some evidence of remaining oil retention flaking scrapes. There are places where parts of it stood exposed, and maybe where chips grime got in. One mark looks like a wear ridge at first, but is in fact a mark from the edge of the gib. The surfaces either side the mark still have some flaking.



	

		
			
		

		
	
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The underside is not pretty, but again, there are suggestions of remaining flaking. That view is being photo-bombed by a good view of the graduated dial. I get along with it OK by using one of those binocular headbands (as us older guys do), but now that I look at the image, it has me decided that it was always just too small, and hard to read.




*The Acme Screw Backlash*
Even as it is, if I put in the 1/4" UNC 20TPI grub screw, the backlash reduces to a more usable level. Taken apart, I see it clearly needs replacing, maybe with some better made contrivance. I can have it soldier on, while using the lathe to make another, but I have in mind to use a little mold box, and make one out of bronze loaded JB-Weld. I have seen some remarkable videos of things done to squeeze a cut plastic tube onto a Acme thread, all the while blasting away with a butane torch, then turning the remains into a good-looking nut, but here, such a plan runs into the obvious "Catch-22" of needing the lathe to turn it's own nut. I have a little video  [Good Lord - the video actually turns out to have sound ] !

View attachment SB9-Compound Acme Nut2.mP4


I think the Acme nut is a bit of a disgrace! I am thinking it would not have looked like that originally. It has had a "brazing operation" on it's lower end, possibly split and "squeezed together" a bit, then brazed, as a kind of "reduce the backlash quick 'n dirty fix". In any event, there is a crack in the brazing. Also, it "rocks a bit" in the round hole in the dovetail piece until the grub screw is tightened.



	

		
			
		

		
	
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I did attempt to put a number on the actual axial backlash. This picture is just for laughs. By far the better way is to see what it is on the graduated dial when all is assembled. Here it says 0.012".




*Pitting!*
The adjuster handle. It was always like that since I got it, but I was not going to sniff at it, because the whole lathe with drawers, 4-jaw chuck(s), and tooling had only taken $147 bucks. If I don't shine it up a bit, then in the face of a paint job, it will definitely lower the tone of appreciations among compound aficionados. I am just not sure how best to go about it. I don't know how to turn on spheres, it's a distraction, and this whole work was to try and get something going to make the part for XRF sensor anyway!

OK then - warts & all I said, so here it is! It is not going to stay that way! I have to wonder why it looks so much worse than most other bits on the lathe, which seem to be in better condition, and mostly lived drenched in oil.




So there we have it. Somewhat picture-heavy, a bit off-putting - I admit, but hopefully here I reap the benefits of what to do to fix it up. Regarding the compound nut, that must surely only be allowed to live long enough to turn up it's own replacement!


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## Ulma Doctor (Feb 28, 2021)

the patina looking brown color is iron oxide- iron will rust in minutes unprotected

Q1: i would definitely grind out the weld area, paying special attention to the outer edges, 45° edge chamfer works best especially for joining 2 pieces.

Q2: grind while the cast iron is cold, then preheat
400°F is sufficient, but you can heat up to better than 500°C if you felt it necessary
(i usually only pre-heat to around 400°F)

Q3, personally i would braze the weldment with low fuming bronze or silicon bronze.
but, if you are gonna stick weld, i would go to the 55% Nickle rod as it will be easier to clean up post weld
the 99% rods are nice, but they are expensive and very difficult to deal with post weld- you are pretty much stuck with grinding for post op's with 99% rod

Q4: Wood ash, sand, earth, vermiculite, all would be acceptable to slow cool- a welders blanket could also be employed
the insulating material, whatever is used, doesn't need to be hot- just make sure it is not frozen

Q5: anytime we mess with heating and cooling things we get a huge chance for warpage.
the slower things are heated and cooled, the more they tend to stay straighter
when i repaired the compound on my SB11, i scraped it in afterwards
you may or may not have problems in this regard, if you stay to the lower end of the pre-heat temperature range

as far as the compound nut, i would not attempt repair when making a new one is very simple-
you'll spend a bunch of time on making repairs to a worn out nut that may be marginal with the best of repair.
i can make a nut for you if you don't have the inclination.
they can also be purchased for ebay too
on a side note, delrin can be bored and tapped slightly undersize to grasp a worn acme screw tighter
this doesn't eliminate backlash, but the felt backlash effect is lessened

if you were to find or make a rock polisher, you could easily make the handle look good as new
add some sand, glass, and/or silicon carbide and water. add a couple drops of dish soap.
let the rock polisher do the work for a day or 2 


let me know, if you need a nut made
i'd be happy to make one for you


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## graham-xrf (Feb 28, 2021)

Ulma Doctor said:


> if you were to find or make a rock polisher, you could easily make the handle look good as new
> add some sand, glass, and/or silicon carbide and water. add a couple drops of dish soap.
> let the rock polisher do the work for a day or 2
> 
> ...


I thank you kindly, and I would take you up on the offer, if or when my own attempts get totally screwed up!  

That is a good suggestion about a tumbler polisher. If they can shiny up rocks, they can do metal.
I saw a video of a re-purposed car polisher. I mean the kind that vibrate sideways instead of a rotate buffing. They are not so good as car polishers, but if bolted to a container which is suspended over a bucket using bungee elastic cords, you can shake up stuff with various media. I think the example was to clean up a carburetter.

Are the parts of these handles held together with screw threads?


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## benmychree (Feb 28, 2021)

The trick regarding welding cast iron is ending up with a machinable weld, which is far from guarenteed.  If the weld is hard, unmachinable, you are screwed; I believe that the best course of repair would be the idea of machining the broken part away and securing a new steel part with screws, I have seen this done several times, and it works well.


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## graham-xrf (Feb 28, 2021)

benmychree said:


> The trick regarding welding cast iron is ending up with a machinable weld, which is far from guarenteed.  If the weld is hard, unmachinable, you are screwed; I believe that the best course of repair would be the idea of machining the broken part away and securing a new steel part with screws, I have seen this done several times, and it works well.


This very point is, I understand, what motivates the use of EniFe-C electrodes, also known as "55s", and also using 99%Ni. A ferro weld would pretty much guarantee to be non-machinable highly stressed variable hard zones, if you could get a fusion adhesion at all. Also, on cooling, even if slow, the part ends up stressed, and can develop cracks because cast iron has very little strength in tension.

We start with the stuff the lathes were made of, called cast semi-steel, which had less carbon and silicon. This stuff is tough, and impact resistant, though there are limits, hence the breakage, but we know there is some strength in tension. The other choice of using 99% nickel weld is the "safe" one in the sense that nickel is non-ferrous, and cannot make a phase with carbon. There is more ductility, though there are, I think, other stress issues related to expansion coefficients, but this aspect I don't know.

You could be right, and I hear you well, and also you be John, who definitely knows stuff. Part of the motivation to first give the weld a try is because my ability to get my mill out of it's crate and powered is pretty much blocked for the present because of building operations.

If this scheme messes up, and the casting remains in enough of one piece, then cutting away the T-Slot top, and making a bolt-on can perhaps be the backstop. If that transpires, there is no question that I will remember that "John told me so"!


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## SLK001 (Feb 28, 2021)

As for the weld, are you planning on building up the missing material with a rod?  If so, do you have a gas grill (outside)?  You're going to want to get the part to about 500ºF before you start.  Build the weld up slowly (one layer at a time) and then close the grill and give the part about 10 minutes to stabilize, then add another layer.  Repeat until you have built up enough metal to cover the missing area.  Close the grill cover and let the part soak for about 30 minutes.  Lower the temp about 50ºF every 30 minutes down to 200ºF, then turn off the grill and let the part cool.


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## graham-xrf (Mar 1, 2021)

SLK001 said:


> As for the weld, are you planning on building up the missing material with a rod?  If so, do you have a gas grill (outside)?  You're going to want to get the part to about 500ºF before you start.  Build the weld up slowly (one layer at a time) and then close the grill and give the part about 10 minutes to stabilize, then add another layer.  Repeat until you have built up enough metal to cover the missing area.  Close the grill cover and let the part soak for about 30 minutes.  Lower the temp about 50ºF every 30 minutes down to 200ºF, then turn off the grill and let the part cool.


A little detail.. Is this stuff done by welding on it _while_ it is over a gas grill?

I had thought to keep it heated between weld passes using a propane torch, and then transfer it into the box of wood ash, or even put it into the woodburner, covered in wood ash, and let it take all night to cool down. I would have a thermocouple on it to keep an eye on temperature, just because I do have one, but I have heard things called "temple sticks" can be convenient. You "draw" a line with them. If the line happens because the tip melted, you know the temperature range. I have never used them yet - still looking them up!

[Edit: I might have guessed that "temple sticks" is a utterly useless search term unless you want every kind of Krishna-neo-hippy incense]!
[You have to spell it right. "Tempil Sticks".  Tempilstik brand]


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## gonzo (Mar 1, 2021)

_ would just find one on ebay and buy it. Probably not a lot of $$$_


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## 682bear (Mar 1, 2021)

They are not expensive on ebay, but what would it cost to have it shipped to Great Britain?

IDK... I would probably attempt to repair it first, anyway, just because it might 'further my education'...

-Bear


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## graham-xrf (Mar 1, 2021)

gonzo said:


> _ would just find one on ebay and buy it. Probably not a lot of $$$_


They are available from eBay.co.uk  from local sellers.
It varies a lot. £4.50 (*$6.25*) for one 177C (350F) in UK with free postage.

Same thing, choose a temperature from a choice of three, but you get only one stick..
Wow! £12.50 =$17.37 plus £3.50 = $4.86. That's *$23.24* for one!
eBay is definitely a place you have to shop around, and read the words carefully.

On another deal, 4 x 50C sticks (that's low temperature) for $34.75 including postage..
.. which works out at *$8.60* each.

Call me "HM tightwad", but I will likely just measure the temperature. Even my (eBay) digital multimeter came with a K-type thermocouple probe, and a Tempilstik or two adds up to a reasonable fraction of the whole instrument with free postage!

I know the temptation of a bolt-on repair is strong, but I think getting to grips with a heat assisted weld, and getting it back in a de-stressed condition after a controlled cool-down is an adventure I would rate as something that I would be proud of, and give me a big buzz if I get it right. Even if things go wrong, I can hardly regret trying!


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## SLK001 (Mar 1, 2021)

graham-xrf said:


> A little detail.. Is this stuff done by welding on it _while_ it is over a gas grill?
> 
> I had thought to keep it heated between weld passes using a propane torch, and then transfer it into the box of wood ash, or even put it into the woodburner, covered in wood ash, and let it take all night to cool down. I would have a thermocouple on it to keep an eye on temperature, just because I do have one,



Yes.

A propane torch will allow the temp to fluctuate too much.  A TC is probably just a waste of time.  Also, your part is relatively small, so any time taken to move it somewhere else to cool would drop the temp too much.  Better to just leave it in the grill and to slowly lower the heat.


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## graham-xrf (Mar 1, 2021)

SLK001 said:


> Yes.
> 
> A propane torch will allow the temp to fluctuate too much.  A TC is probably just a waste of time.  Also, your part is relatively small, so any time taken to move it somewhere else to cool would drop the temp too much.  Better to just leave it in the grill and to slowly lower the heat.


OK - you all have got me onto this in a deeper way.
Despite the impression one can get from those cheerful guys on YT making it look like  10 minutes fun with a welder, and plugging either the welder or the rods, getting this right involves some planning.

Pretty much, every move is choreographed. The preparation of all the resources, and hot things. The sequence of what gets done when, right down to thinking through the weld lay plan. I will get it hot, and keep it hot, right through the whole thing.
*
The Handle*
I had a go at the corroded handle. I used a 5mm wide little file to take out the pits, using the "rock it around the curve" filing technique, but this time, in two directions at once, while rotating the part. Apparently, this ensures what is filed off comes off a sphere. It seems to have worked OK.

 I followed with some abrasive paper grades to take out the file marks, and get it somewhat shiny. I plan to give it a dose of vinegar nickel, but here is what we have so far. Its a "before 'n after" thing






Sure - I was messing with the bit I knew how to fix while thinking about the novel weld fun yet to come!


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## finsruskw (Mar 1, 2021)

Your cross slide nut looks nothing the one in my 9A


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## erikmannie (Mar 1, 2021)

If you were paranoid (like I am), you could bolt down & AND weld (and/or braze) the broken off part of the compound.

I would mill it down to where it was missing a rectangular prism, machine the missing rectangular prism with 2 countersinks on top, tap original compound, bolt down your new machined piece, do a plug weld over the countersunk washers & bolts, and then probably braze the existing seams (.001” is good for brazing). The mechanical connection should be enough for the job, & the brazing serves to fill the gaps & serve as insurance.

Welding the bottom seam would be tough because it is hard to get to; that is why I would choose brazing there. You know that if you are going to both braze and weld, you need to do all the welding first.

Be wary of prexisting oil in the original compound. Another reason to opt for fasteners.


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## brino (Mar 1, 2021)

gonzo said:


> _ would just find one on ebay and buy it. Probably not a lot of $$$_





graham-xrf said:


> They are available from eBay.co.uk from local sellers.
> ........... a Tempilstik or two adds up to a reasonable fraction of the whole instrument with free postage!



I thought @gonzo was talking about buying a new top-slide............not just a temperature crayon.........now I'm not sure!


As to the business at hand. I would definitely braze NOT weld, as @Ulma Doctor recommends.
Just considering the possibility of temperature induced issues, the brazing temperature is much lower.
Pre-heat and slow cool still recommended, but likely not as critical due to the lower temps involved.

.....of course I have the oxy-acetylene rig and have had a few successes with brazing myself.

I wish you all the best success and please let us know how it goes!

-brino


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## erikmannie (Mar 1, 2021)

Brazing is always nice because it doesn’t threaten the base material.


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## graham-xrf (Mar 2, 2021)

erikmannie said:


> Be wary of prexisting oil in the original compound. Another reason to opt for fasteners.


Erik - In the "belt 'n braces" theme, I had thought about what would make a stronger thing. Sure, I could figure up a design, freely helping myself to all sorts of smarts from the internet, but I wanted it just to look like what it is, work a whole lot better, have a large dials upgrade (when it becomes capable of turning it's own stuff), and a better paint job.

Re: Oil in the weld. I plan to grind the torn metal surface away back to clean, and likely give it a last minute go-over with a Dremel burr when it's hot. There cannot be oil left inside the metal - can there?


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## graham-xrf (Mar 2, 2021)

finsruskw said:


> Your cross slide nut looks nothing the one in my 9A


Do tell!
As it happens, this is the only one I have ever seen. I don't know what a proper one is supposed to look like.
Now you got me looking for old catalog PDFs, and paging through "_A Guide to Renovating the South Bend Lathe 9" Model A, B & C Plus Model 10K_".


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## graham-xrf (Mar 2, 2021)

brino said:


> .....of course I have the oxy-acetylene rig and have had a few successes with brazing myself.
> I wish you all the best success and please let us know how it goes!
> 
> -brino


I don't have oxy-acetylene. I once helped a pal get an acetylene cylinder to his place, and then I got to watch him light it, and make the smoky yellow flame turn blue.

I principle, I could persuade the Sherman welder into "lift-TIG braze mode". I have definitely considered all the braze options.We had those amazing pics from Ulma Doctor where he went to what looked like brazing fine art sculpture on a compound that had been chewed by a crash with a chuck!

This Old Tony has explored TIG brazing, taking it to a high skill..
Here  -> 




WeldingTipsandTricks explains aluminum bronze TIG braze, as opposed to silicon bronze braze for a vise repair, saying the braze is stronger provided the part is not going to be temperature cycled, like an exhaust.
Here - > 




I will check the thermal expansion coefficient of the 45/55% ferro-nickel alloy, but we already know it has to be close enough to cool without too much stress, because that is what the alloy was developed for in the first place. I get it that getting the weld to "take" is the key thing. This is where brazing can easily "wet" on the join, and from then on, easily joins to itself. Pure nickel famously wets to iron, which is why it was traditionally used for repairs to higher carbon cast iron. I know that once non-ferrous braze metal is in there, you can never weld again short of cutting it all the way back to iron. If I try the weld first, and it turns out to be a fiasco, I can maybe try the braze as the alternative.

In the way folk are at HM, nobody is going to come onto me bad if I get it totally screwed up (other than a few laughs), so I don't mind having you see all see what happens. I just have to figure out some sensible heat treat arrangements, because kitchen grill is _verboten_!


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## SLK001 (Mar 2, 2021)

finsruskw said:


> Your cross slide nut looks nothing the one in my 9A



That's not the cross slide nut - it's the compound slide nut.  It looks as it should.


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## finsruskw (Mar 2, 2021)

Whoopps!!
Sorry about that!!
Whatever it is, sure looks like it has seen better days!!


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## Tim9 (Mar 2, 2021)

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I’m big on repairing lots of stuff. But there’s a lot of stress on T-slots. Especially the mount for the lantern or QCTP
For under 40.00, I’d buy a used one and then work on the rest. Old saying... you can’t polish a turd.


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## SLK001 (Mar 2, 2021)

Tim9 said:


> I’m big on repairing lots of stuff. But there’s a lot of stress on T-slots. Especially the mount for the lantern or QCTP
> For under 40.00, I’d buy a used one and then work on the rest. Old saying... you can’t polish a turd.



This is quite true.  However, there isn't much to lose in trying the repair.  The repair is mostly cosmetic, so the bulk of the stresses would be absorbed by the intact T-slot.  

If the repair fails, the OP could easily fall back on a used compound.


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## Tim9 (Mar 2, 2021)

I totally agree SLK. I’ll be the first to admit that not too long ago, I had no other options but to repair this sort of thing. Back then, I just couldn’t afford 50.00 , so I absolutely bronze brazed cast iron things like this. As I often would say.... I’ve got more time than money so there’s little to lose.

in fact... on my first Atlas 618.... I repaired just this sort of break on the compound. It was never perfect, but at the time I just couldn’t afford to buy anything on EBay. I say another thing often.... Poverty sucks but it is what it is. No point in crying and don’t forget..... it could always be worse.


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## graham-xrf (Mar 2, 2021)

SLK001 said:


> This is quite true.  However, there isn't much to lose in trying the repair.  The repair is mostly cosmetic, so the bulk of the stresses would be absorbed by the intact T-slot.
> 
> If the repair fails, the OP could easily fall back on a used compound.


I could make the 9A "donate" it's compound to the 9C, but you can see where that leaves the 9A.

Purchasing a compound in the UK looks pretty much not going to happen. There are some beat up lathes on eBay "parts only", where there is a whole 9C with chucks and change gears for £225. Free collection in person only, long journey through one of the world's harshest lockdown,  and nothing else on it I need. There are some parted-out bits, "as seen" in pictures that are too small and not zoom-able, all at bunkum prices, many with a postal charge from the USA. I don't know about customs import duties. Last time I purchased from USA/Canada, it stopped at the port until a fee was paid.

Here is a sample..




Note that £107.61 is *$149.57* ! It becomes £170.46 when you add in the postage.
Then convert to dollars -> *$236.93*   (What?)
I am not inclined to play on these terms.
Here is a UK eBay link -> SB9C 42" for restoration

If rigidity and strength is is an issue with these, then a variation of the "New T-Nut lip held on with screws" route might be to machine away _both _the T-nut top ledges, and fix in thicker strong steel replacements, each held in with  four high tensile countersunk screws, possibly made somewhat permanent with Loctite 638.

Right now, as I progress on this learning curve, I begin to feel I have less and less to lose. $40 for a compound body replacement sounds impossible when just a used compound nut by itself is like this -->



At today's exchange rate, that comes to *$75.20 !! *What's with the £35.17 (*$48.88)* to post a little harmless thing that weighs 32.3g (1.14oz) ?
I already have a worn nut. Why buy another? I would rather play with trying out my own bronze-loaded epoxy version.

Getting back to the weld fix, I think if I get it (slowly) up to something very hot, and keep it hot while welding, then after the weld, take the heat up higher, heat soak and slow cool. It can go in insulation, and take 16 or 20 hours to cool if that seems a good plan. So far, the costs are not high, and the learning is intense!


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## martik777 (Mar 2, 2021)

Americans don't realize how lucky they are to have access to a huge marketplace and cheap USPS rates. I am in Canada, 25kms from the border but cannot buy anything from the USA without paying enormous shipping rates like yourself. Luckily I can have some items shipped to the border town and pickup for a $2 fee but it's still a PITA.  It is usually cheaper for me to have items shipped from China than the USA.


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## SLK001 (Mar 2, 2021)

martik777 said:


> It is usually cheaper for me to have items shipped from China than the USA.



Same here... I can buy something from China and it is cheaper to ship from there than from across town.


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## Tim9 (Mar 2, 2021)

martik777 said:


> Americans don't realize how lucky they are to have access to a huge marketplace and cheap USPS rates. I am in Canada, 25kms from the border but cannot buy anything from the USA without paying enormous shipping rates like yourself. Luckily I can have some items shipped to the border town and pickup for a $2 fee but it's still a PITA.  It is usually cheaper for me to have items shipped from China than the USA.


I totally agree. And although I don’t really identify with either political party on every issue, I get really ****** when I think about the fact that America’s leaders gave a Communist country most favored nation trade status. It’s actually cheaper to ship something from China to the USA than it is to ship something from Canada or Mexico. It’s crazy. 
   We should be building and supporting the America’s . Most favored nation trade should be with North and South America. Granted, that’s not going to fix everything. But it’s just one more impediment for Canada -USA trade when it costs 25.00 to ship something across the border. And it’s certainly not helping Central America. If the economy was just a little better in Central America, then maybe we wouldn’t have a border immigration problem. What the heck is going on in Washington DC. Just so broken on the stuff that’s important.

I know we aren’t supposed to get political and I tried to keep this post worded so it wasn’t too Party affiliated. But, somethings really messed up when I can buy something from China and the postage is 4.95 while if I order a screwdriver from Canada..... I pay 14.00


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## graham-xrf (Mar 3, 2021)

Tim9 said:


> I get really ****** when I think about the fact that America’s leaders gave a Communist country most favored nation trade status. It’s actually cheaper to ship something from China to the USA than it is to ship something from Canada or Mexico. It’s crazy.


Far enough back in history that I think by now we are allowed to mention it  - we Brits did worse! There was a time (1946) when we shipped 10 Rolls-Royce Nene Jet engines to the USSR (as it was at the time). Then, another 15 in 1947, ending up selling 55 jet engines at a fixed price.

1947 was hardly "wartime". By then, surely, Russia was no longer "an Allied nation".
What happened was one Artem Mikoyan was actually invited to visit the Rolls-Royce factory.
Stalin was shocked, reportedly saying "What idiots would sell us their jet engines?"
Also what happened was obvious and inevitable. Dozens of Americans were shot down by MIG-15s with a 100mph advantage!

As a lad, I would like and trust "Made in USA", or "Product of Great Britain". The stuff was quality, and affordable. Something is very skewed if now, we can't get an item of a trusted American brand from Buffalo to Calgary for a price that is not an unreasonable fraction of it's value. Russians, Germans, Japanese, and yes - even the very best of Chinese are not inherently smarter, nor more gifted than the rest of us!


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## graham-xrf (Mar 3, 2021)

finsruskw said:


> Whoopps!!
> Sorry about that!!
> Whatever it is, sure looks like it has seen better days!!


Completely agreed. I don't intend to give it  better days to come. It's last ironic task, brimming with poetic justice, is to perhaps participate in the making of it's own replacement - maybe.

You get me thinking..
*Loads*
The entire load of cutting forces through the machine shoves on the little lead-screw, usually at some angle, because most folk try not to let the adjust handles of the cross slide, and the compound get too near to each other. If they don't actually clash, then at least they might limit the size they can be.

Then further down, the load goes through the cross-slide nut, this time shoving the threads into shear parallel to the axis. Everything we care about in rigidity and accuracy goes through these small things. OK - not _all_ the forces. Some transfer via a fractionally tilted pin, or rotational moment onto dovetail slides, but in principle, they are easily driven into their "better days" being a thing of the past. If the lathe(s) survived beyond the anticipated war end, they become "repair consumables".

*UHMW, PEEK, Turcite, Rulon, Tivar, et al*
So what is the deal with using plastics for Acme Nuts? Can they take the load? Are they short-lived. Are they cost-effective?
I had wondered if a strong epoxy (Marine JB-Weld loaded with bronze powder might work, especially if potted over a lead screw coated with car wax to get a ready-made Acme thread. Here is a video which is gross in some ways, but anyway..

--> 




Would you prefer true "metal-to metal"?


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## SLK001 (Mar 3, 2021)

graham-xrf said:


> Would you prefer true "metal-to metal"?



I don't think that any of the plastics can take the load.  If they "compress" during use (as in threading), then that will result in an oversized thread.  Since the compression would be different for each loading, you might just end up chasing your tail trying to hit your mark.

Chalk me up for a "metal-to-metal" solution.


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## martik777 (Mar 3, 2021)

I recently made 2 crossfeed nuts for my 2 9A's, one from Al 6061 and one from black delrin. I already had the LH 7/16-10 acme tap so it was quite easy. Both work with close to zero backlash but I cannot account for durability in such a short timeframe, however, others have observed no major wear issues with Delrin.


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## graham-xrf (Mar 3, 2021)

martik777 said:


> I recently made 2 crossfeed nuts for my 2 9A's, one from Al 6061 and one from black delrin. I already had the LH 7/16-10 acme tap so it was quite easy. Both work with close to zero backlash but I cannot account for durability in such a short timeframe, however, others have observed no major wear issues with Delrin.


OK - we know that various plastics can be tough and wear resistant, but how about your impressions of deflection and rigidity. I mean the kind of things @SLK001 was mentioning. Also, does the point at which "chatter screech" begins, get adversely affected.

If I were to set about making a replacement, I would be thinking single point threading, but I did notice a 10TPI ACME tap in HSS costs about £17.50 (that's about *$24.32* bucks). It may be OK for aluminum, or brass, or Delrin nylon, but I thought it would be hard going for that size of thread in any kind of steel.

This is where we are allowed to suggest any and all sorts of Acme screw/nut combinations.


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## SLK001 (Mar 3, 2021)

graham-xrf said:


> If I were to set about making a replacement, I would be thinking single point threading, but I did notice a 10TPI ACME tap in HSS costs about £17.50 (that's about *$24.32* bucks). It may be OK for aluminum, or brass, or Delrin nylon, but I thought it would be hard going for that size of thread in any kind of steel.



Remember the tap has to be a LH version.  If you use bronze or steel, single point to ~85-90%, then finish with the tap.


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## graham-xrf (Mar 3, 2021)

SLK001 said:


> Remember the tap has to be a LH version.  If you use bronze or steel, single point to ~85-90%, then finish with the tap.


Eh! ?? It's right in front of me and I am looking at it . See the pictures and the video in post #1. That is definitely a *RH* _right-hand_ screw.

Which way things move depends on which of the slides has the screw, and which carries the nut.Turning clockwise on the compound pulls the nut pegged into the underside dovetail _towards_ you, like any RH nut. Since it can't come towards you, the compound with the screw moves away from you.

The situation is reversed for the carriage cross slide. Here the screw is mounted into the lower slide, which is the "non-moving" one, and the nut is in the moving part. Turning it clockwise requires a *LH* thread, to have the slide with the nut, and hence the compound and tool above, to move away from you, towards the work.

[I must admit, I always have to look at these things twice, and if I have to turn on a bolt with a spanner, and it's driving towards me, I always get it wrong! ]


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## SLK001 (Mar 3, 2021)

graham-xrf said:


> Eh! ?? It's right in front of me and I am looking at it . See the pictures and the video in post #1. That is definitely a *RH* _right-hand_ screw.




Oops, my bad...  I just automatically thought "left handed" tap.  You're correct - it is a righty!


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## graham-xrf (Mar 3, 2021)

@SLK001 : Can one reasonably do this without using a tap at all?

I have the ACME gauge, and a tool that came with the lathe that looks like the right one that should be OK after a minute or two touch-up with a hone. Getting an ACME right, turning on the thread sides separately, with a flat bottom is not as straightforward the more usual 60° tool advancing square-on. Maybe I should just bite the bullet, and order in the tap. You can see why I was considering the metal-loaded mold short-cut


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## martik777 (Mar 3, 2021)

Here's one for $18.49 inc shipping: https://www.ebay.com/itm/New-1pc-AC...536389?hash=item4dbadd2305:g:9YcAAOSw9yZdDiPP

Definitely go with delrin and make a few. I would not be too confident using that import tap in steel or brass, maybe ok after a partial single point machining.


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## graham-xrf (Mar 3, 2021)

martik777 said:


> Here's one for $18.49 inc shipping: https://www.ebay.com/itm/New-1pc-AC...536389?hash=item4dbadd2305:g:9YcAAOSw9yZdDiPP
> 
> Definitely go with delrin and make a few. I would not be too confident using that import tap in steel or brass, maybe ok after a partial single point machining.


Yes - hardly any backlash, and just change them if they get worn.
Would you anticipate any of the compression under load issues as described by @SLK001 in post #31?

I agree about the tap in metal. The advice is to get it 90% cut, and then finish with the tap.


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## martik777 (Mar 3, 2021)

graham-xrf said:


> Yes - hardly any backlash, and just change them if they get worn.
> Would you anticipate any of the compression under load issues as described by @SLK001 in post #31?


I have not experienced any differences from the metal nut other than no backlash and I've made approx 30 parts with 5 tens tolerance since installing the delrin nut.  I no longer use my compound for threading but feed with the crossfeed only.  I would focus my attention on that before spending too much time on the compound.


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## SLK001 (Mar 3, 2021)

graham-xrf said:


> @SLK001 : Can one reasonably do this without using a tap at all?



It's just as easy as regular threading.  It is a 3B class thread, which is the most difficult part of cutting (close tolerances).  Keep your compound spindle handy and test the fit after every cut once you get close.


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## Larry$ (Mar 3, 2021)

graham-xrf said:


> because kitchen grill is _verboten_!


Only when someone catches you!


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## graham-xrf (Mar 4, 2021)

Larry$ said:


> Only when someone catches you!


Definitely not going there! Kitchen is to have planned makeover anyway, but even so ..
*
Serendipity ??*
I happen to have 2 x 7kg butane gas cylinders + regulator left over from when old _chez caravan_, purchased as already 2nd-hand in 1998 finally reached a condition where it had to be disposed of in 2018. One cylinder is full, the other about half-full. It seems natural to have them be useful again. Then I compare the cost of a eBay gas hob to the cost of variously, a ACME tap, a replacement nut, some fire bricks, etc.

Looky here!!



So I clicked "Buy it now". The HM collection of rabbit-holes has now led me into (partial) heat treating. This gas hob, with some _ad-hoc_ modification on top to contain and connect to the compound, becomes a major resource not subject to censure for sneaking time on the kitchen cooker. Also, it is acquired at the price of doing single point ACME threading (sans tap) learning curve.
 I will probably expend a good deal more than that practicing both the weld, and making ACME threads.

Now also, I am bounced into reading Machinery's Handbook to discover what are class 3B threads, because it begged the question..
"What other classes are there"? Must so stop with the distractions!


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## SLK001 (Mar 4, 2021)

graham-xrf said:


> Now also, I am bounced into reading Machinery's Handbook to discover what are class 3B threads, because it begged the question..
> "What other classes are there"? Must so stop with the distractions!



There are 6 classes of threads - three for external (1A, 2A and 3A) and three for internal (1B, 2B and 3B).  Class 1 threads are the loosest fit, Class 2 are a little tighter and Class 3 threads are the tightest fit.  They are just really tolerance classes.


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## Tim9 (Mar 4, 2021)

Just my take. Delrin and the high end plastics will work pretty good for cross-slide nuts. It’s usually done as a delrin insert inside the bronze housings of said worn out bronze nuts. And the advantage is less backslash.

    But, this thread is about a broken t-slot. That’s a totally different animal in my opinion. J-b weld will never hold those forces.

    Personally, I’d try bronze braze for that repair. But that’s not an easy repair because after you braze it then it needs to be milled perfectly squared, otherwise the tool post ends up being cocked.
  I’ve tried it and I never really got it perfect.
now, in my defense.... that was when I first started in this hobby. I didn’t even have a mill...so I had to file it with a hand file. Filing a t-nut perfectly isn’t easy. Damned tool post always wanted to rock a little.


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## graham-xrf (Mar 4, 2021)

Tim9 said:


> Just my take. Delrin and the high end plastics will work pretty good for cross-slide nuts. It’s usually done as a delrin insert inside the bronze housings of said worn out bronze nuts. And the advantage is less backslash.
> 
> But, this thread is about a broken t-slot. That’s a totally different animal in my opinion. J-b weld will never hold those forces.
> 
> ...


Oops - please don't misunderstand.
I started out wanting to weld the T-nut, because the remains of the slot, while able to hold the tool post, will be considerably weakened. The original lantern post had been replaced by a square rotatable, and then lately, by a quick-change tool post, which are larger. The edge of the T-nut is partly over the break.

*It's a weld repair and a Acme nut replace*
I noted the backlash was a bit much, but when I took it apart, to clean up for the weld, there I discovered the less than wonderful Acme nut. It turns into two operations to fix. It seems wrong to put such a wrecked Acme nut back in a repaired compound. I guess mentioning the messed up stuff in the compound, additional to the weld repair is "off topic", but I am contemplating doing stuff to my compound generally considered serious, and risky. The commentary so far has been extremely valuable. Such a lot of stuff I needed to know, plus a lot of alternative options. I am still getting up the nerve to actually hurt metal, but it is going to happen. I fully appreciate that things could go badly wrong, and that some choices  may be unwise for my level of skill. Nobody need say "I told you so"!

*Re: Filing stuff to a controlled flat surface.*
Some guys have a muscle memory that works almost as linear as a shaper, but we are not made of unyielding slides. If the file is going to inevitably "rock", then one solution is to have the work rock with it. The same trick sword sharpeners use. Make a little plywood base with brackets to mount a rod to pivot on. Fix a nail onto each the ends of the (wooden) rod, and hang it between V cuts in plywood stands. Clamp the work to the plywood one-axis gimbal. Now, as you file, it does not matter if the file tilts, because the work rocks to follow it. It's especially effective for draw filing.


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## SLK001 (Mar 4, 2021)

graham-xrf said:


> *Re: Filing stuff to a controlled flat surface.*



Do you have access to a surface grinder, or shaper, or even a mill?  One of these could easily flatten the top surface.  I would say that using a vertical mill to flatten the underside of the weld would make things really simple

In a pinch, you could file the weld down to flush by hand, then smooth things up with some emory paper.  It really is doable.


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## martik777 (Mar 4, 2021)

Fixture it in a 4 jaw and  true up the top with a facing cut.


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## Tim9 (Mar 5, 2021)

I’m sure you can get it flat. Trust me. When I was hacking my 618 cracked compound... I really knew nothing. And I got it good enough to use the lathe for a few months. But when I saw one at a really good price... I snatched it up on EBay.
  So you’re going to be able to fix yours in my opinion. On the Acme nut... there’s tons of ways to get it better. FWIW, I’ve read many descriptions of fixes of nuts with Delrin and JB. In the end, I just purchased a brass nut from one of the EBay sellers who makes replacements. Not as good as a bronze OE nut, but much cheaper. New nut and a new screw and problem fixed. I still have some backlash. But that’s the nature of the beast.  We’re never going to eliminate all of the backlash.


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## graham-xrf (Mar 5, 2021)

SLK001 said:


> Do you have access to a surface grinder, or shaper, or even a mill?  One of these could easily flatten the top surface.  I would say that using a vertical mill to flatten the underside of the weld would make things really simple
> 
> In a pinch, you could file the weld down to flush by hand, then smooth things up with some emory paper.  It really is doable.


I do have the brand new Cormak mill drill, and vise, and clamps, parallels, and a MT3 chuck with ER32 collet set, and even a DRO kit.
BUT..
It's still in it's crate, under the welder 




From what you say, I think I have to agree. Fooling about with files and hand-held grinders when the mill resource is right there to finish it properly is just not sensible. Building operations or not, I will have to force some space to set it up temporarily, and get the right milling cutter to do T-slots.

I have been grinding on it!



One thing I have to watch out for. The present situation of UK for imports is suddenly strange, I think because UK is now no longer in the European Customs Union. eBay stuff from China on "Free Postage" suddenly attract substantial charges before delivery, which is VAT and customs duty. I am very glad I got the mill purchased just before all this happened.

Perhaps a 6mm wide cutter, about 20mm diameter might do. So now I am checking out milling cutters. I am not sure about what is best used on the top face. There will be weld sticking up. Does it need a face mill, or a fly cutter? That is a bit one can reasonable get flat with a file.


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## Tim9 (Mar 5, 2021)

Since you have a mill and a welder... maybe get some nickel 99 rods....and do a few light  passes ... filling in the missing piece. Make sure to preheat the compound to about 250 degrees F.  After each pass...let it cool about 5 minutes. I’d go on the low side of the recommended amperage so that it kind of lays down better and fills in more than heavy penetration which I tend to get when I set my welder to the higher amp settings.

once you’ve fill it where you want it, dunk it in a bucket of sand...dry sand...and let it cool slowly. Sand will work....vermiculite insulation is even better. But the main thing is to let it cool slowly so you don’t get cracks.

   Then mill off excess. i was thinking about welding steel on top but cast iron and steel welded together just don’t mix well. Tends to cause cracks as it cools.
   Plus, if you add a support piece on top of it.... make sure the added height doesn’t screw up your tooling of your quick change tooling.
Sometimes it’s better to not overthink this stuff in my opinion. Just go the easy route. Weld some nickel 99 and mill off the excess.

I think you could get by with a 13mm or 1/2” end mill. Just do multiple passes and go easy on the cuts. Yeah, a fly cutter would be nice, but I don’t think you absolutely need that. Nickel 99 rod mills fairly easy.


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## SLK001 (Mar 5, 2021)

For the top, I like martik777's idea of chucking it up in a 4-jaw and facing off the top, then sanding out the milling marks with some fine emery paper (put the paper on a piece of glass, then polish off the top with the compound face down).


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## graham-xrf (Mar 5, 2021)

martik777 said:


> Fixture it in a 4 jaw and  true up the top with a facing cut.


I love it!
BUT - there is a "_Catch 22_" !


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## SLK001 (Mar 5, 2021)

graham-xrf said:


> I love it!
> BUT - there is a "_Catch 22_" !



What's the catch?  No 4-jaw chuck?


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## graham-xrf (Mar 5, 2021)

SLK001 said:


> What's the catch?  No 4-jaw chuck?


4-Jaw chucks are there, but the lathe that would turn them now has no place to mount it's toolpost! 
There are limits to how far one can take the very satisfying route of having a lathe fix up parts of itself!

I am not so afraid of filing something to a good finish. See in post #12, I filed the quite deep dings and corrosion pits out of spheres, using the "rock with two tilts while rotate" filing technique.


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## ericc (Mar 5, 2021)

You could make a plinth to replace the compound and be able to use the lathe for turning.  I just watched a YouTube video of someone turning the compound on his mini-lathe.  He said, no toolholder, we'll improVISE.  This is a pun, by the way.


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## graham-xrf (Mar 5, 2021)

ericc said:


> You could make a plinth to replace the compound and be able to use the lathe for turning.  I just watched a YouTube video of someone turning the compound on his mini-lathe.  He said, no toolholder, we'll improVISE.  This is a pun, by the way.


Erik, what you say makes sense! I have noted that Quinn Dunki (of Youtube "Blondihacks") has mentioned that some will make up a block fitting that does away with the compound entirely, in the interests of rigidity, but in a way that it can be put back for the few times it really is essential.
Are we talking of a steel block with a threaded hole in it to mount the toolpost, somehow attached to the cross-slide?

Quite a lot of what I need to make, some parts for the household, some for my machining interests, are depending on that I fix the lathe. Even the XRF project now needs parts made on a lathe.


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## martik777 (Mar 5, 2021)

Don't you had a spare lathe?

Anyways, the compound has a round base that can be held by the 3-jaw so no need for a 4 jaw. I just tried this with my 9A's compound. Light cuts recommended.

To operate without a compound you could make a fixture that fits the cross slide hole,  preferably with the same angled cylinder as the compound but  a straight cylinder should work with light cuts.

You could always reassemble the wounded compound to make these parts.

Edit:  The newer SB9's (circa 1950+) have 2  threaded holes on the top of the cross slide just below the hole where the compound fits into. These may be used to secure a fixture to hold a tool bit.


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## graham-xrf (Mar 5, 2021)

martik777 said:


> Don't you had a spare lathe?


[/QUOTE]
I did! I did!. That was the first one I took to pieces (the 9A).
I was happily restoring bits of it, and the 9C was helping. Then the old belt broke on the 9C, and shortly after, with a partly fixed belt, I got a QCTP - and so discovered the broken compound. I tried to ignore it, and put everything back together. Now hampered by building operations, and having to be moved out to it's new home anyway, I thought to do some repairs, and I bought a brand new serpentine belt to be spliced.


martik777 said:


> > To operate without a compound you could make a fixture that fits the cross slide hole,  preferably with the same angled cylinder as the compound but  a straight cylinder should work with light cuts.


The shape of it is already forming in the mind - but that would be a future feature, probably one step behind my notion of converting a pair of ex-brake discs into a steady rest..


martik777 said:


> You could always reassemble the wounded compound to make these parts.


This too, has not escaped my thoughts. What I hope to do is fix the compound broken T-slot, but just put the other parts together with a lick and a promise to re-visit them. Then the 9C can make it's own Acme nut. 

I will post pictures of how this goes. I might have to start over if it messes up, but hopefully not.


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## martik777 (Mar 5, 2021)

I edited my last reply while you were replying re: cross slide threaded holes.....

BTW: lol, I made a steady from ex-brake rotors - not the best plan


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## graham-xrf (Mar 5, 2021)

martik777 said:


> I edited my last reply while you were replying re: cross slide threaded holes.....
> 
> BTW: lol, I made a steady from ex-brake rotors - not the best plan


Re: Threaded holes in the cross slide to "bolt things to". I am going to take a look, but my lathes are 1947 for the latest one. I can perhaps drill and thread a couple of holes, instead of making a block with a strange cone shape under.

What was the downside to re-purposing brake disc metal?


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## martik777 (Mar 5, 2021)

The rotor was only .210" thick so was not too rigid and I was not able to weld as it was cast iron. Maybe a thicker rotor would work better.


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## graham-xrf (Mar 7, 2021)

martik777 said:


> The rotor was only .210" thick so was not too rigid and I was not able to weld as it was cast iron. Maybe a thicker rotor would work better.


Hmm - if the discs I have are cast iron, then hopefully I will have got past the "weldability" issue by the time I try them. I think car discs have to be made with a goodly proportion of steel, maybe like wrought iron, because crude cast iron could shatter in a wheel, or get stressed up by wheel nuts. This whole thing is about welding on cast iron semi-steel, and we want that solved..

Welding up a lathe steady, in my mind, is made up of _two_ discs, with the slides for the steadies welded in between. My Merc discs appear to be two discs already, separated by ribs for air cooling. Just one of those type might be stiff enough.


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## ericc (Mar 8, 2021)

Careful!  I was on a walk, and I found a broken piece of brake rotor disk in the road.  I brought it home for doing some experiments with a welder and gobbed on 6011 with no preheat.  It stuck well and hard.  It took a lot of hammering to break it.  Much later, this emboldened me to try to weld up a follower rest from a Chrysler brake rotor disk.  It behaved completely differently.  The metal bubbled and burned away like Styrofoam.  I tried TIG silicon bronze.  Same problem.  I ended up having to burn the carbon out with a torch and brass braze it.  This held.  Moral of the story: brake disks are not made out of the same metal.  Welding on these pieces were as different as night and day.


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