# 9 x 20 half nut problem



## savarin

I believe I may have a major problem with my lathe (generic 9x20) 
This is the second time I have had the half nut threads wear away. 
The first time it happened I hadnt had the lathe long and the problem was swarf collecting inside and preventing the nuts from fully closing. 
I sorted that out by making a new lever, placing the detents further apart and adjusting the mechanism ensuring the nuts fully clamped onto the lead screw and regularly cleaning out any swarf. 
I stripped and reassembled and re adjusted it this time, most of the thread had gone but I needed to finish a job so had a go. 
A couple of things I checked. 
The saddle travels from end to end and the lead screw doesnt move up, down, in, or out so its in alignment with the worm and tail stock end bearing and the half nuts clamp firmly to the leadscrew. I will also check out the leadscrew for straightness some time but it doesnt wobble in the tail stock end is not bolted down so I'm assuming its pretty straight. 
BUT 
When I engage the threading lever to clamp the half nuts to the lead screw the lead screw flexes inwards towards the bed. I ensured the remaining threads were fully engaged.
This has caused wear in the worm housing bearing at that position as well so its been going on a long time. 
I have thought of placing some shims behind the worm housing to move it inwards towards the lead screw and possibly facing the tail stock end bearing down to move the lead screw inwards the amount it seems to flex. 
The threads on the lead screw also appear to be very sharp on their edges and in particular where the keyway is cut and from the colour of the dust seems to be actually cutting the half nuts. 
Major questions - 
Where can I purchase the half nuts without the 12 to 16 weeks delivery time I'm being quoted in Australia? 
Is it feasible to dress the complete thread on the lead screw to remove all the sharp edges? (or worth it) 
Are the mods mentioned above worth doing?
Can anyone suggest any other things I could do? (other than purchasing a better lathe) 
Thanks


----------



## hman

I just checked Grizzly's website.  T the half nuts (P/N P4000741) appears to be available.  I'll need to phone them Monday to confirm, and also to verify that they're sold by the set.  Wouldn't want to order 1, thinking it was a pair, and just get one of them.  I'll also check the lead time.  Once I have all the info, I'll send you a PM, and we can figger out how to get them to you in the most expeditious manner.

I have a 9x20 (Grizzly G4000), and have noticed the sharp corners on the leadscrew at the groove.  I didn't worry about it, once I'd verified that there were no burrs.  Sharp corners themselves shouldn't be that big a deal.

I'll also do the checks you did regarding leadscrew movement, both when the carriage is moved and when the half nuts are engaged, and let you know the results.


----------



## savarin

Thanks John, thats awesome.
Update on the half nuts pushing the leadscrew towards the bed.
The apron is held on with two bolts only, with some experimenting I found that by engaging the half nuts whilst the apron is loosely held then tightening them aligns everything up as it should be. One problem solved.


----------



## Downunder Bob

Im think from memory your generic 9 x 20, as you call it, uses a single shaft for lead screw and feed shaft, with a longitudinal keyway, to drive the feeds. It will always collect swarf, and as it turns around the swarf will act like steel wool on the internal threads of the hlf nuts, rapidly accelerating the wear.

Some of the more modern versions have incorporated a telescopic sleeve covering the shaft in an effort to stop this happening Another method is to set up a brush on the headstock end of the saddle to keep the shaft clean as it rotates.


----------



## Cadillac

Sounds like the leadscrew roughness might be your problem. Along with alignment issues. Might look into getting a new leadscrew if it has sharp or ruff threads. Any pics of leadscrew and worn half nuts


----------



## savarin

I'm convinced your correct Bob, I had thought of the brush idea but never got round to it.
I'm going to experiment with a bicycle innertube held in a couple of clamps to see if it can compress and stretch sufficiently to act as a cover.
Been looking for old clocks for the springs to make a telescopic cover but havnt found any so far.
Cadillac, the actual lead screw is a very good smooth thread, its just the edges are sharp and the part where the keyway is cut out is also sharp.


----------



## Cadillac

When I bought my jet 9x20 It was my first lathe and previously used. I ended up tearing her down assessed and replace any worn parts I thought needed replacing. I had replaced the worm gear and had found it had slop left to right within mount. I ended up putting a brass washer on each side which made the worm snug in housing. I also replaced the drive engagement gear so the apron is nice and tight. 
When I reassembled carriage I ended up stoning the entire keyway your talking of. Was ruff like you say. Then with leadscrew mount  loose I aligned the shaft to the bed of the lathe. Then I aligned the apron to the bed and screw. With having the half nuts engaged on the screw. Seemed to work very well haven’t had any issues. 
One thing I love about my bigger lathe is it has the coil covering on the leadscrew left and right. Would think it can be bought but may not wanna hear the price. Ive also seen where people have installed a deflector on cross slide to divert the chips away from leadscrew kicks them back between the bed rails.


----------



## markba633csi

Perhaps make a new set of half nuts from a different material? Bronze possibly?


----------



## Bob Korves

Another issue on many lathes is that the half nuts are not lubricated often enough.  Out of sight, out of mind.  That is an issue even on lathes like my Kent 13x40.  Neither the feed gear pinion or the half nuts are lubed by lubing the normal lube points.  They need to be manually lubed regularly to make them last.  Cleaning and lubing the lead screw regularly helps, but not enough.  The manual says to manually lubricate them.  My lathe came from the factory with spare half nuts and a spare feed screw Edit, gear.  Those were the only spare parts that came with the lathe.  The factory obviously knows about it...

Good job, savarin, of getting the lead screw better lined up with the half nuts.  If the factory does not do it, then we have to.


----------



## RJSakowski

Two thoughts on  your rapid wear of the half nuts. First, with the longitudinal slot and sharp edges, it may be working like a tap shaving away the half nut threads. Second, if the half nuts are not completely disengaged when in the power feed mode, the sharp edges of the threads may be shaving the threads.  An examination of the wear pattern should tell you which.


----------



## savarin

Looking at the brass coloured oil it seems that yes its cutting very finely. 
It will be a long job but I think very worthwhile


----------



## C-Bag

My 9x20 had the half nuts not set up correctly so that's why they wore quickly. Don't know if it was previous owner or factory. I replaced them with Grizzley units. Like Savarin in order to get the correct alignment had to set the half nuts and then tighten the saddle. I also rigged an old tooth brush to clean the lead screw but wasn't really happy with the mount. I recently came up with something better. Still a tooth brush but old brushes off our SoniCare brushes that have really strong magnets in the base. This really simplifies mounting after modding the brush. This seems to knock all the swarf off the lead screw. I also put a bellows between the carriage and under the chuck and it overhangs the side eliminating the amount of swarf that can even get slung onto the lead screw.


----------



## BROCKWOOD

I retrofitted mine with the telescopic sleeves.

 Before 






After


----------



## stupoty

RJSakowski said:


> Two thoughts on  your rapid wear of the half nuts. First, with the longitudinal slot and sharp edges, it may be working like a tap shaving away the half nut threads. Second, if the half nuts are not completely disengaged when in the power feed mode, the sharp edges of the threads may be shaving the threads.  An examination of the wear pattern should tell you which.



my old 9x20 only has the half nuts for power feed so that put a lot of extra ware on them.

Stu


----------



## savarin

Heres a pic of the worn half nut, it looks ok in the pic but theres virtually no real thread left.




Whilst awaiting the new ones I thought I should clean and adjust as much as I could.
Todays job was to check out the cross slide, it had a tiny rock between two corners.
A bit of scraping got it sitting flat with full contact for the full length.
Next I will be drilling and tapping for two more gib screws.
Now another question, Would this be a good idea and worth doing to improve cross slide oiling?
Grinding out hollows on the black lines and feeding them with a ball oiler, if so how many oilers per side?
and Is there a better pattern?


----------



## Cadillac

Savarin that is a good way to get oil on the slides. I would recommend not so many zigzags.  I did this exact mod about a year ago on my jet 9x20. I ended up doing my saddle which for the V groove I put the Oiler directly above the v to get both sides. Then for the flat part I did what your doing. I put three perpendicular lines almost the width of slide. Then connected each groove with a long angled groove that went from top to bottom of groove. Like this |\|\|. Only as long as slide. I put oilers at each end also. The trick is to not break through the sides so the oil has a void to stay in.  The mod worked great and the fact that their were no provisions for oil. Oiling the flat rail made a big difference for me with saddle movement. It now glides as it should. What’s nice is after filling ports you can see how the wipers contain and spread the oil from the inside. Not mixing oil with chips moving slides hoping it gets under there. 
 Oh and you want to try and cover the whole area of the slide with the groove. Meaning any spot that has no groove running over it will wear different so it might wear a ledge on sliding surface. Like putting a line parallel with slide. The opposite part would never wear causing a ledge and problems in the future. That’s why the angle going the width of slide is a better option just watch your ends.


----------



## RJSakowski

stupoty said:


> my old 9x20 only has the half nuts for power feed so that put a lot of extra ware on them.
> 
> Stu


Yes, the same as my Grizzly 602 and my Atlas/Craftsman 6 x 18.  

The Grizzly 9 x 19 (G4000) and IIRC, the Enco and HF as well, do have the separate feed system.   Savarin had mentioned the keyway that is characteristic of the separate feed so presumably the half nuts are only engaged for threading.  Which is why is would be puzzling to see so much wear on the half nuts.

If the half nuts didn't completely disengage when the power feed was being used, they would be sliding over those sharp lead screw threads which would be wearing them down.


----------



## stupoty

RJSakowski said:


> Yes, the same as my Grizzly 602 and my Atlas/Craftsman 6 x 18.
> 
> The Grizzly 9 x 19 (G4000) and IIRC, the Enco and HF as well, do have the separate feed system.   Savarin had mentioned the keyway that is characteristic of the separate feed so presumably the half nuts are only engaged for threading.  Which is why is would be puzzling to see so much wear on the half nuts.
> 
> If the half nuts didn't completely disengage when the power feed was being used, they would be sliding over those sharp lead screw threads which would be wearing them down.




Ow yes now you say that I did indeed miss that in his post 

Stu


----------



## Cadillac

As RJ said I’d be curious if the thread is worn the whole circumference or just at the opening of half nuts. That would tell a lot.


----------



## C-Bag

Seems like some kind of drip cup that drips oil on either the half nut or lead screw would be a good idea. As little single point threading as I do that half nut should last forever as its only engaged for threading. It also seems like a good idea to get the proper die for the lead screw and chase the threads. Maybe take a look at the power feed to see if it's somehow causing that slot in the lead screw to develope a burr while in use. That's one thing I've noticed with this 9x20, lots of attention to all the details because of the variable QC. Like the half nuts not being properly adjusted in the first place. Just never know what's going to bite you in the butt until it's too late.


----------



## savarin

I did a lot of fettling when I first recieved this lathe but as it was the first lathe I had ever used there was everything I didnt know or have experience with.
I adjusted and checked everything I could after heaps of research on line. 
Mostly I used logic to work out how to do it and Cletus's books.
The first set of half nuts were damaged in a crash, totally my fault.
I rebuilt the worm carrier with brass inserts that stopped the key dropping out from excessive end play on the worm.
drilled larger holes in the half nut dove tails so they could be aligned fully and removed all the play.
Made sure they opened and closed fully.
Everything worked well and I have cut heaps of threads with no problems.
I think the main problem was having removed the saddle a couple of times since and never checking how they clamped before tightening the saddle bolts is what caused the problem this time.
I've run a quick experiment regarding the bicycle innertube cover idea and it looks like a good possibility. I will report back if I get it working.
There must also be a better way of preventing swarf from entering the rear of the saddle.
Oh how I love these type of problem solving exercises


----------



## BROCKWOOD

Seems Half Nut not disengaging enough might be a good thing to look into.

I crashed my cross slide early on. Since rebuilding it, I cannot recall if the auto feed is reversible when the chuck is not reversed. Did I mess up & lose that function or just wish I had it? Grizzly G0773 must be very similar to all of yours.


----------



## hman

C-Bag said:


> My 9x20 had the half nuts not set up correctly so that's why they wore quickly. Don't know if it was previous owner or factory. I replaced them with Grizzley units. Like Savarin in order to get the correct alignment had to set the half nuts and then tighten the saddle. I also rigged an old tooth brush to clean the lead screw but wasn't really happy with the mount. I recently came up with something better. Still a tooth brush but old brushes off our SoniCare brushes that have really strong magnets in the base. This really simplifies mounting after modding the brush. This seems to knock all the swarf off the lead screw. I also put a bellows between the carriage and under the chuck and it overhangs the side eliminating the amount of swarf that can even get slung onto the lead screw.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> View attachment 279234
> View attachment 279235


C-bag, I thought this was a fantastic idea.  Just had a bit of concern about losing some leftward travel, as the toothbrush in this position would run into the QCGB ahead of the carriage.  I did a bit of looking at my own 9x20 and came up with this alternative:

Step 1 - I had some brass brushes, as shown in the first photo.  The orange handle brushes came from Home Depot, the grey handles form someplace else, long forgotten.  I cut the handle off one and plucked out the tufts sticking out on the diagonal.  Found a place on the underside of the carriage where the head would fit, though the bristles were "too long" and bent against the leadscrew.  So I milled a bit off the back of the head.  This let the bristles reach all the way into the leadscrew threads without too much bending.  Added two threaded holes.






Step 2 - Found some 2" x 1/16" aluminum angle and cut off a chunk about 1" wide.  Narrowed down the part under the brush, added two holes for brush mounting and two more for mounting on the carriage.  Shortened the mounting "leg."





Step 3 - Mounted the brush assembly on the leading face of the carriage, below the leadscrew (after first having checked that there were no carriage parts in the way, either during threading or power feeding).  The low profile of the brush mount allows full leftward carriage travel.





Step 4 - Unless power feeding or threading, I've always disengaged the QCGB by lowering the selector all the way down to disengage the gears.  My theory is that this saves wear and tear on the leadscrew, as well as reducing noise.  I turned the leadscrew to place the drive notch at the bottom, marked the top of the coupling with some paint.  This will be the "default" leadscrew position and will let the brush clean the power feed groove whenever the carriage is run back and forth.  When the leadscrew is turning, the brush will clean the threads.





UPDATE:
I sent Savarin a spare brush setup for his 9x20 lathe.  Turns out that his lathe is "the other kind" of 9x20 - with the carriage crank on the right side of the carriage.  Mine is on the left, as shown in my third photo.  He had to mount his brush outboard of the carriage (see post #34), because his did not have the nice little cubbyhole underneath the leadscrew on the left side.  Check your own lathe for the location of the crank, and plan accordingly!


----------



## Downunder Bob

hman said:


> C-bag, I thought this was a fantastic idea.  Just had a bit of concern about losing some leftward travel, as the toothbrush in this position would run into the QCGB ahead of the carriage.  I did a bit of looking at my own 9x20 and came up with this alternative:
> 
> Step 1 - I had some brass brushes, as shown in the first photo.  The orange handle brushes came from Home Depot, the grey handles form someplace else, long forgotten.  I cut the handle off one and plucked out the tufts sticking out on the diagonal.  Found a place on the underside of the carriage where the head would fit, though the bristles were "too long" and bent against the leadscrew.  So I milled a bit off the back of the head.  This let the bristles reach all the way into the leadscrew threads without too much bending.  Added two threaded holes.
> View attachment 279306
> 
> 
> Step 2 - Found some 2" x 1/16" aluminum angle and cut off a chunk about 1" wide.  Narrowed down the part under the brush, added two holes for brush mounting and two more for mounting on the carriage.  Shortened the mounting "leg."
> View attachment 279307
> 
> 
> Step 3 - Mounted the brush assembly on the leading face of the carriage, below the leadscrew (after first having checked that there were no carriage parts in the way, either during threading or power feeding).  The low profile of the brush mount allows full leftward carriage travel.
> View attachment 279308
> 
> 
> Step 4 - Unless power feeding or threading, I've always disengaged the QCGB by lowering the selector all the way down.  My theory is that this saves wear and tear on the leadscrew, as well as reducing noise.  I turned the leadscrew to place the drive notch at the bottom, marked the top of the coupling with some paint.  This will be the "default" leadscrew position and will let the brush clean the power feed groove whenever the carriage is run back and forth.  When the leadscrew is turning, the brush will clean the threads.
> View attachment 279309



That looks like a very well executed mod, should work a treat. I like the concept of marking the coupling so that the power feed groove is always parked in the down position.


----------



## gzoerner

John,

That's a super improvement.  I'll be doing it on my G4000.  Thanks for sharing.

Glen


----------



## savarin

I like that brush  idea, so simple so brilliant.
Grooved the cross slide and de-burred yesterday. 
But, I think I may have made a bit of a boo, I forgot the cross slide doenst fully cover the saddle so the oil grooves at each end will be exposed allowing the oil to squirt out when pumped in. Hopefully its still better than no oil and will help.
The oilers are in and two more gibb screws are in.
Starting on the saddle today.
The "V" way showed a wear stripe on each side almost the full length but the flat only showed wear on one end about 15mm long and a narrow strip at the other end about 3mm wide and 50mm long.
I've started scraping to obtain full length contact and its getting better, there is also a casting defect half way along running almost the full width across the flat.


----------



## hman

Regarding the cross slide ... did you groove the slide or the saddle?  It's best to groove the shorter of the two (ie., the slide).  The slide being on top, gravity is also your friend - less chance for crud to fall into the grooves than if they're on the bottom.  But as you've said, it's gotta be better than no oil!


----------



## savarin

The slide is grooved.
In thinking about this further I think it will be a method of flushing the oil ways of crud. Move to one end and pump then move to the other end and pump. Or pump when there is a small overlap at each end which will flush from both ends replacing the old oil with fresh.
Just trying to find a positive here


----------



## savarin

I cannot believe how much I had to scrape the saddle to fit the bed.
Added two ball oilers to the "V" groove and two to the flat way, just have to add an oil groove to the flat.

It felt very smooth when pushed from end to end (without the gibbs)
Got to admit its getting better
cue for a song


----------



## Cadillac

I had watched a video on utube I think Stefan G where he put grooves in the compound slide. He talked a lot about finding the limits of the travel of compound so that the groove didn’t go past the saddle. Which as youve found releases the pressure of oil. Either way oiling is way better than not. She will sing like a dream. Good job.


----------



## savarin

Made new rubber wipers that have the added bonus of holding a bit of the oil back in where it should be.
Eagerly awaiting the new half nuts being sent to me from hman along with a couple of other bits. How awesome and amazing is that.
That beats waiting for 16 weeks and probably longer considering the Chinese new year will be upon us by the time they got round to sending the order.


----------



## savarin

Whilst waiting for the half nuts I've decided to extend the cross slide screw for a bit more travel, add real bearings to the shaft, make it M10x1 to make the travel calcs easier. The original M8x1.25 thread is very worn in the middle with a lot of backlash but very firm at each end of its travel so it does need replacing.
What would be the best material to use for a new lead screw here?
I have a heap of stainless rod I could use, would this wear ok do you think?
And would brass be ok for the nut?
I have a bit of scrap from a marine pump that I think is bronze of some type, maybe I should cast a chunk for the nut from that if brass is too soft.
Made a start on the new larger handle from a zinc alloy ingot and on the vernier ring and dial from a small length of 60mm dia leaded steel from somewhere (I think it was a drop I was given)


----------



## savarin

Once you start fettling you just cant stop. 
I have a length of alloy 60 x 100 mm long so that will be the bracket, the handle I've turned from a zinc alloy ingot. 
I made a 100 segment circle scale held in the end of the spindle as an indexing aid to scribe the 0.01mm divisions. 





The saddle stop is clamped with a "G" clamp so the divisions are all the same length. 




Once I finished the divisions I knurled the end, 




then bored the middle out with a hole saw then parted it off. 




the finished dial sans numbers sitting on the handle with a very smooth fit. 




The bearing on top will be in the extended bracket. 
I know this flexi lathe cant hold this kind of accuracy but I though with the 1mm thread and 100 divisions on the lead screw it will make the length calculations easier (I hope).
I'm still uncertain what material to use for the lead screw. 
I have enough stainless I could use but am unsure if it will wear ok. 
The nut will be either brass or some cast bronze if I melt it.


----------



## savarin

There are times when I hate turning, reducing the centre of the extension support bracket could only go one pass at a time due to this.





Any way the parts from John Herrmann (hman) have arrived so its geterbackproper.
I took a lot of care getting everything adjusted to as spot on as I could and ensuring the half nuts closed from both sides equally took a bit of fiddling but we got there.
Next I added the brass brush John sent, so simple, so effective, I love it






and with the cross slide shield I think swarf will find it very difficult getting in there.






with the half nuts replaced the old ones are virtually smooth on one side and the other one has half the width of the thread worn away.
I really hope all the care I took ensuring they clamp up equally will prevent this from happening again.






Does it all work now?
Yep
single point M8 x 1 in stainless.
 These are for the bearing clamps on the binocular.


----------



## savarin

Started on the cross slide shaft but its a long process turning that down from 16mm to 10mm.
However, like all my projects I've been side tracked again.
I'm attempting to make a vernier scale, no real reason in this instance just to see if I can.
The idea is to add a vernier scale to the cross slide dial of my lathe. 
On a flexi 9x20 its a bit of nonsense but what the hell.
I have engraved 100 divisions around the dial using a scale I printed off from this site.
http://www.cgtk.co.uk/metalwork/reference/divider  as you can see above.
This hopefully will give me an advance of 1/100 of a mm of cross slide travel per division so with the vernier theoretically it should advance 1/1000
I'm thinking if I print off a scale with 90 divisions to the same diameter size as the 100 scale and use that to engrave another dial but just use 20 divisions this should give me 9 divisions in the space of 10 divisions on the original scale.
A quick test by printing both scales and overlaying them to see through the 90 to the 100 underneath seems to bear this out as with the zero on each scale in alignment the 9th division of the 90 scale sits on the 10 mark on the hundred scale.
or should it be a 110 scale where the number 10 sits on the 9 of the hundred scale.
Which one would be the correct version?
Am I on the right track here or just blowing bubbles?


----------



## Bob Korves

savarin said:


> Am I on the right track here or just blowing bubbles?


Resolution and accuracy are two different concepts.  Increasing resolution does not necessarily increase accuracy.  On your smaller Chinese lathe, I hope it will make you feel better...


----------



## savarin

As I said Bob, On a flexi 9x20 its a bit of nonsense but what the hell. 
It will look cool and as we all know - cool beats practicality.


----------



## savarin

I eventually used the 110 segment scale, it gives 10 divisions in the space of 9 divisions on the main dial.
Heres all the parts




Assembled




Its a nice smooth action with the two bearings.
I'm really happy with the M10 x 1 mm thread, the longest I've cut and very smooth




Now I have to mill off the excess aluminium from the extension bracket and I haven't worked out how yet.




If you look closely you can see the brass shim where I over bored the bearing recess.


----------



## BROCKWOOD

Looking good! I like the way you are tightening your specs & correcting your dial. Mine shows 80 divisions for 0.010 of movement per revolution. Gonna follow your lead on this!


----------



## hman

savarin said:


> Now I have to mill off the excess aluminium from the extension bracket and I haven't worked out how yet.
> View attachment 281568


Consider this ... There's really no need to continue the dovetail profile on the part.  It has no guiding or alignment function.  I _think_ all you really need to do is clear the slide.  So you might consider cutting on something like the yellow outline illustrated below.


----------



## savarin

Definitely the way John, thanks. 
Still working on a holding method.


----------



## savarin

Started milling the waste material with an end mill but it was very rough finish.





So I ground a broken tap to a small raked flat tip cutter and used a small boring bar to remove the rest.




Now its being filed down for the final fit.
Meanwhile -
can anyone see a reason as to why I cannot cut a channel or drill a hole for the extended cross slide lead screw at the end of the cross slide so the nut can travel a bit further?
Would a channel weaken the saddle too much?




As its in bits to do all this plus replacing the headstock bearings I thought why not go here as well.
If I was designing this I would have placed a roller bearing there for the end of the lead screw but thats probably a bit of overkill.


----------



## savarin

I decided I needed a key for the handle so thought a woodruff type would be the easiest to make. 
I ground a thin cutter and fixed it into a boring bar.
The bar was held in the chuck and the shaft I wanted to keyway cut was held in a wedge type QCTP holder.
I set the height so the cutter was centered on the shaft and just kissing it.
Locked the saddle and cross slide.
Then the cringe bit.
Gently loosened the holder and adjusted its height  so the cutter started cutting, gently tightened the holder which had the propensity to raise the shaft parallel again and cut a little more. Repeat untill the slot is deep enough.




Not a brilliant photo but hopefully you can get the drift.


----------



## Downunder Bob

G'day Charles, I'm still constantly amazed at the new ways you can create to do the impossible with next to nothing. Your continued use of excessive overhang to get good results is mind boggling as always.

Carry on you've got me beat. I look forward to the day when I'm next in Qld, and I can see some of your toys.


----------



## savarin

Look forward to a beer Bob.


----------



## savarin

as you can see there is a brass shim under the holding screws.
The test bar didnt use the shim and a too heavy a cut actually spit the shaft out of the holder making a neat row of divots along its length.
The cutter touched, gripped and levered the shaft out one rotation at a time.
All good fun.


----------



## jcp

"The test bar didnt use the shim and a too heavy a cut actually spit the shaft out of the holder making a neat row of divots along its length.
The cutter touched, gripped and levered the shaft out one rotation at a time."

Saw this happen in the shop where I worked. Operator was cutting key seats in a 2 7/16ths x 12' shaft. Machine was a Summit universal mill with a 10 x 54 table set up in horizontal arrangement. Hold down clamping was inadequate and pulled the shaft into the cutter. Amazingly the cutter didn't break. Pulled the entire length of shaft past the cutter. It did trash the cutter mandrel.


----------



## savarin

Cut the keyway in the handle by grinding a carbide (horrible) small boring tool thinner and used the saddle handle to gently cut away the slot.
I used the same process of lowering the tool holder after every pass.




To stop the chuck rotating I locked it with my indexing system.




I have got to get my act together and clean, polish and blue all my made tools in a forlorn attempt at beating the humidity rust bug.


----------



## BROCKWOOD

Here in Louisiana, humidity is a given. Yet with a gas fueled water heater for the house actually located in the garage where I do my machining, no worries of rust at all. I also periodically spray WD on bare surfaces & run a small electric heater while working.  Your project is looking good!


----------



## savarin

Heres the thread inside the handle after burning out the broken tap then running the intermediate tap through. 





Then bolted in place


----------



## Downunder Bob

savarin said:


> Heres the thread inside the handle after burning out the broken tap then running the intermediate tap through.
> View attachment 282873
> 
> 
> Then bolted in place
> View attachment 282874


Looks like a pretty good reovery


savarin said:


> Look forward to a beer Bob.



Me too,.


----------



## Downunder Bob

savarin said:


> Cut the keyway in the handle by grinding a carbide (horrible) small boring tool thinner and used the saddle handle to gently cut away the slot.
> I used the same process of lowering the tool holder after every pass.
> View attachment 282665
> 
> To stop the chuck rotating I locked it with my indexing system.
> View attachment 282666
> 
> I have got to get my act together and clean, polish and blue all my made tools in a forlorn attempt at beating the humidity rust bug.



Charles, have you tried Inox MX3 will stop the rust.


----------



## savarin

Downunder Bob said:


> Charles, have you tried Inox MX3 will stop the rust.


 Which one Bob? I've just looked on line and there are a variety of Inox MX3 products.


----------



## Downunder Bob

savarin said:


> Which one Bob? I've just looked on line and there are a variety of Inox MX3 products.




It's called Inox MX3 lubricant, and comes in different container sizes so suit yourself, a spray can is convenient but expensive, a small hand squirt bottle, a 5l container and bigger, you don't need the FG grade unless your working on food machinery.

All the other products like MX2, MX4, MX5 etc are for a variety of uses they are pretty self explanatory on the website. The little hand squirt bottle is a convenient way to try it. Ive been using the 5L bottle now for some time and have a few small squirt bottles around the shop. I use it for protecting metal that is stored outside, especially freshly cut, and or welded. I even give a light spray onto a new roll of MIG wire when I fit it into machine.

Also all my hand tools, also use it as a cutting fluid on lathe, drill press and band saw. It's very good on difficult metals like SS and Al, I don't have a corrosion problem even though shop has evap air con.


----------



## savarin

Todays job was making a new cross slide nut from some brass sponge as a test. I will eventually do this in bronze and hopefully solid metal not a spongy mess.
Chopped a chunk from some failed casting and faced it off.





Flipped it and faced again




I kept it as large as I could just in case.
then turned the fixing spigot.




Drilled and tapped then filed to fit the gap in the saddle casting




With such a long thread it is very smooth and not much side play.
I need to add a couple of shims on the top of the boss as if I tighten the fixing screw very tight the movement becomes stiffer.




All bolted up and a nice smooth movement with extended travel both fore and aft.
When the M10x1 die arrives I will cut the shaft 12 mm shorter and use two M10x1 locknuts to fix the handle.
Compared to the original its now  joy to use.


----------



## Downunder Bob

Waste not want not, still as creative as ever.


----------



## dkwflight

Hi
I thought the threads on the lead screw were pretty sharp on my lathe. I ran a triangl file in the threads as the lead screw turned. This de burred thand softened the edges nicely.
I may have to try the brush idea.
I tried making a cover for the screw nut it did not work too well.
The best thing I did was to make a shelf to catch the chips mounted on the screwa the hold the traveling rest.


----------



## Downunder Bob

savarin said:


> Todays job was making a new cross slide nut from some brass sponge as a test. I will eventually do this in bronze and hopefully solid metal not a spongy mess.
> Chopped a chunk from some failed casting and faced it off.
> View attachment 283343
> 
> Flipped it and faced again
> View attachment 283344
> 
> I kept it as large as I could just in case.
> then turned the fixing spigot.
> View attachment 283345
> 
> Drilled and tapped then filed to fit the gap in the saddle casting
> View attachment 283346
> 
> With such a long thread it is very smooth and not much side play.
> I need to add a couple of shims on the top of the boss as if I tighten the fixing screw very tight the movement becomes stiffer.
> View attachment 283342
> 
> All bolted up and a nice smooth movement with extended travel both fore and aft.
> When the M10x1 die arrives I will cut the shaft 12 mm shorter and use two M10x1 locknuts to fix the handle.
> Compared to the original its now  joy to use.



Love the look of that vernier on the dial, Real cool, and as we all know, cool beats practical all the time.


----------



## dkwflight

I replaced the OEM potmetal half nuts with a set from Grizzly. They seem to work fine except I cannot thread under power using the threading dial. I get multiple tool paths being very careful to get the dial in the exact right/ the same engagement place.
I find an issue with the gearing that makes it mandatory to keep the half nuts engaged.
Problems with the lead screw. I find you have to move the carriage as far to the right as possible with the right side bearing loose engage the half nuts. Then tighten the cap screws.
If you cannot get the lead screw in the right position you may have to enlarge the mounting holes in the bearing as I did.

You also have to de burr the lead screw. I ran a triangle file in the thread grooves under power  and also with a stone clean up the key way. This  improved the half nut operation.


----------



## dkwflight

This pic shows the tool paths I got while power threading. most of the blue is gone


----------



## dkwflight

This pic shows 5 passes making a scratch pass. with the half nuts remaining engaged


----------



## savarin

Had another thought, I went down the same route of shimming the lead screw fixings at the tailstock end to get everything aligned but still had problems.
I found that loosening the apron screws, engaging the half nuts with the saddle at the chuck end and you could watch the tailstock end of the lead screw come into alignment.
Tightened the apron screws then the tail stock end, disengage the half nuts, run the saddle to the tail stock end, loosen the leadscrew screws again and engage the half nuts and see if the leadscrew moves, I am assuming the leadscrew is not bent.


----------



## dkwflight

Hi
For me the definitive answer for threading is to shut off the motor before engaging the half nuts. This way I was sure the half nuts were engaged exactly on point and fully engaged before starting the motor.
Thanks
Dennis


----------

