# Getting rid of the compound slide?



## Pcmaker (Aug 15, 2018)

I've read a few times in this forum that some posters got rid of their compound slides on their mini lathes. Apparently, it makes it more ridgid for parting off. 

I'm thinking of doing the same thing. What are the pros and cons? So far, I haven't really had the need to use the compound and it's very hard to part off because of ridgidity problems on my 7x12. Do I just drill and tap the cross slide for the QCTP bolt?


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## WarrenP (Aug 15, 2018)

People usually make a new block that the compound sits on because you want the tool the same height as it was. There are videos on utube showing how to do it. You might need measurements for your lathe but otherwise should help. I was having trouble parting until I got a "T" cut off blade, helped alot. Without the compound its harder to cut tapers,angles,etc. But you can always put it back on if you need it, just more work.


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## TerryH (Aug 15, 2018)

Done like this. I just ordered the plate to do my G0572. Same principle on your mini.


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## Pcmaker (Aug 15, 2018)

Besides easier parting, what other benefits do you get by taking out the compound slide?


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## mikey (Aug 15, 2018)

Everything is more rigid. Turning, boring, parting are all improved. It works for all lathe but is especially beneficial for light machines.


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## Cadillac (Aug 15, 2018)

Like you I had heard of the same. More rigidity overall eliminating the compound. So I took a chunk of steel I had lying around and went at it. Dimensions the only thing that matters is keyway slots and your height. For the height here is a good time to see how your toolholders sit in the qctp. All to high make it lower or opposite. Footprint I made a little bigger than compound base. Figured it only strengthens the cross slide the longer it’s made. I ground mine after getting a surface grinder but originally I flycut all surfaces.


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## Nogoingback (Aug 15, 2018)

I replaced the compound on my lathe with a lump of solid steel, and it's now the default setup for my machine.
I only install the compound when it's needed, which isn't very often.   As mikey said, everything is improved due to increased
rigidity, and on my machine it's a bit nicer to work around as well.  It's a very worthwhile modification.


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## Ken from ontario (Aug 15, 2018)

For me facing is one operation that is difficult to do without a compound slide.
Usually with the compound on,I let the tip of the cutting tool touch the face,(with the lathe off), lock the carriage ,move the compound back a couple of thou, turn the lathe on, move the compound forward a few thou  , cut with the cross slide until done,but now without it I would have to move the carriage a couple of thou and that's not an easy task on a mini lathe.


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## Mystery1 (Aug 15, 2018)

TerryH said:


> Done like this. I just ordered the plate to do my G0572. Same principle on your mini.


Nicely done. Makes an amazing difference. I bring the tool holder up to the cuck to align perpendicular to the lathe. Bang on every time.


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## epanzella (Aug 15, 2018)

I replaced the compound with a tool block on both my Logan 11 inch and my Grizzly G4003G. The logan wouldn't hardly part steel at all with the compound but cut fairly well with the block.  The Grizzly parted well but the block made it even better.  Finish in all operations improved as well. Rigidity is the mother of all good things that happen on a lathe. 
Pics below.


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## mikey (Aug 15, 2018)

Ken from ontario said:


> For me facing is one operation that is difficult to do without a compound slide.
> Usually with the compound on,I let the tip of the cutting tool touch the face,(with the lathe off), lock the carriage ,move the compound back a couple of thou, turn the lathe on, move the compound forward a few thou  , cut with the cross slide until done,but now without it I would have to move the carriage a couple of thou and that's not an easy task on a mini lathe.



Hey, Ken,
Facing should not be an issue without a compound mounted on the cross slide. You simply loosen the top nut on your tool post and rotate the tool post to position the tip of the tool in a facing orientation and then lock the nut down. From then on, you are using the saddle feed wheel to set depth of cut and the cross slide wheel or power feed to face. You do not need to use the compound to feed a facing cut.

The only time you really need the compound is when turning tapers. It is also useful when threading if you prefer the step over method with the compound set to 29.5 degrees. Otherwise, the compound/cross slide assembly is just another set of interfaces that provides opportunities for movement (at the gibs). If you can make one, I suggest you consider doing so.


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## Ken from ontario (Aug 16, 2018)

Hi Mike, yes I got the concept when it was brought up ,it just sounds unconventional but I'm willing to try it and see how much rigidity I gain  and at what cost, maybe I should reserve my judgment until I have gone through facing ,turning, parting etc.  with the compound removed.
One reason  I am a bit hesitant  is , I have not had much problem operating my mini lathe  the way it is, and when i faced a problem I always found a way around it , for example I have modified my compound slide by adding two compound locks to it to lock the gib in place and make it more solid during facing/ parting.


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## Pcmaker (Aug 16, 2018)

What size lathe is considered ridgid enough to part off as well as some other procedures? I was thinking of getting an 11 x 27 Precision Matthews lathe sometime in the future


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## Nogoingback (Aug 16, 2018)

That probably depends on which specific lathe as well as it's size.  I can tell you that when I part off on mine
(10" Logan) with the compound replaced parting off goes much better. 

An 11" PM machine would be a huge improvement compared with your 7 X 12.


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## Pcmaker (Aug 16, 2018)

Yep, this time I won't mess around and get the DRO preinstalled


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## Pcmaker (Aug 16, 2018)

What size separates lathe from mini lathe?


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## mikey (Aug 16, 2018)

Ken from ontario said:


> ... for example I have modified my compound slide by adding two compound locks to it to lock the gib in place and make it more solid during facing/ parting.



Yep, locking the compound helps but a solid plinth will still be better. You don't need to do it but if you chose to I think it might be a useful upgrade.


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## Chipper5783 (Aug 16, 2018)

Pcmaker said:


> What size lathe is considered ridgid enough to part off as well as some other procedures? I was thinking of getting an 11 x 27 Precision Matthews lathe sometime in the future


 
As others have said - it depends on the design of the machine.  I have a 11x24 heavy pattern English tool room lathe, vintage 1963.  It weighs nearly 5x what that PM 11x27 does.  Parting off is no problem at all!

The light weight lathes can be made to work (and even work well), it just takes some fussing is all.


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## mikey (Aug 16, 2018)

Pcmaker said:


> What size separates lathe from mini lathe?



You will find that a more useful way to look at lathes is to compare feature sets rather than just size. Most mini-lathes and hobby class lathes are 10" and under; almost all of these are imports. They typically have spindle mounts that involve 3-4 bolts to hold the chuck on or are threaded. They generally will have power feed but that is driven either by the leadscrew or a key that runs in a slot on the leadscrew instead of a separate drive shaft. Many of the cheaper lathes will be change gear lathe instead of having a quick change gear box but if they have a gear box, threading options are limited. Most of these lathes will not have hardened and ground gears, spindles and ways. Of course, the cost for these cheaper lathes is much lower than a full featured lathe. There are many, many other differences that I won't go into here.

There seems to be a clear distinction between the entry level hobby class lathes and what I consider the more serious hobby class lathes; this seems to be somewhere around 11" or so. Here we begin to see hardened and ground spindles with precision spindle bearings, camlock spindles with realistically useful spindle bore sizes, hardened and ground ways, separate power feed shafts, wider/more rigid bed widths, heavier castings, more useful quick change gear boxes, etc. To see this distinction, take a look at the feature set between the PM 1030 and the PM1127 and you'll see what I mean.

The PM 1127 is a lot of lathe for the buck. It isn't as good as the more fully featured lathes but it is a very good example of what I think is a good entry level hobby lathe. Note that there is a thing I call "feature creep". For a few hundred dollars more you can have a PM 1236 and for a bit more you can have the 1236T. This gets you into the discussion between Chinese lathes and Taiwanese lathes, the latter being of higher quality and clearly more expensive. 

Of course, there are other brands of lathes that are heads and shoulders above import lathes. The Hardinge and Monarch lathes, Colchesters, etc. You can still buy a Hardinge tool room lathe for only $60K.

So, what you have to do is learn about lathes and which features are important. It ain't just about size but the features you get or don't get. Some things, like a camlock spindle, are important enough to me to be a deal breaker if the lathe doesn't have one. Does it come with a full change gear set? What are the spindle bearings specs? What kind of warranty? Where is it made?

You may or may not want to look at "old iron". If a project suits you then there are many used lathes on the market as well.

Lots to research but once you narrow it down to what you think you want, ask the guys on the forum who own those lathes and get real user opinions. Then you can decide.


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## whitmore (Aug 16, 2018)

Pcmaker said:


> I've read a few times in this forum that some posters got rid of their compound slides on their mini lathes. Apparently, it makes it more ridgid for parting off.




Since a compound's angle adjustment is no benefit in a parting operation, why not just put a parting tool (upside down)
on the distal end of the cross slide?   Just leave the compound and tool post on in the usual (proximal) position.

Like this : <http://www.hemingwaykits.com/acatalog/Rear_Tool_Post.html>


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## ddickey (Aug 16, 2018)

There's no reason not to that I can see. I have one on mine.


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## Cadillac (Aug 16, 2018)

Ken from ontario said:


> For me facing is one operation that is difficult to do without a compound slide.
> Usually with the compound on,I let the tip of the cutting tool touch the face,(with the lathe off), lock the carriage ,move the compound back a couple of thou, turn the lathe on, move the compound forward a few thou  , cut with the cross slide until done,but now without it I would have to move the carriage a couple of thou and that's not an easy task on a mini lathe.


All that needs to be done to keep track of movements is put a mag base dial indicator on your saddle and zero it out on a hard stop. Then you can move precisely.


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## SamI (Aug 16, 2018)

There are a number of other mods that people have done to their mini lathes to improve rigidity without losing any function.  I fitted angular contact bearings to the spindle and this made a big difference.  In an effort to get my mini lathe up and running again last night I re-adjusted these and have noticed a big improvement in the surface finish when facing.

Tapered gibs is another mod I know a lot of people have done.  I would love to do it myself but I don't have a mill to make them so it's on the back burner for now.

When parting I have found it best to lock the carriage and compound if possible to prevent any movement.  The biggest issue I have is the tool digging in and either snapping the parting blade or stalling the lathe.  I personally found running at slightly higher speeds helped as the lathe had less of a tendency to stall.  Keep the parting blade sharp too - if you try and push a blunt tool into the workpiece then that's a recipe for disaster.


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## Mitch Alsup (Aug 16, 2018)

Pcmaker said:


> What size lathe is considered ridgid enough to part off as well as some other procedures? I was thinking of getting an 11 x 27 Precision Matthews lathe sometime in the future



I have never had any problems parting off with my G4003G 12*36 Even big hunks of steel.


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## RWanke (Aug 16, 2018)

So far I have had no problems parting off on my old 9" South Bend.


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## Pcmaker (Aug 16, 2018)

I need some seriously thick steel to replace the compound slide. Something like 3 inches thick.


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## Ken from ontario (Aug 16, 2018)

That doesn't sound right, 1.625" thick is what I'm thinking.


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## Pcmaker (Aug 16, 2018)

Yeah, I just measured it and these are the dimensions of what I need. Anyone know where's a good place to get it online? Something exact or close enough and I can mill out the rest. I don't think it has to be exactly the same length and width as the block below it.


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## TerryH (Aug 16, 2018)

Pcmaker said:


> Yeah, I just measured it and these are the dimensions of what I need. Anyone know where's a good place to get it online? Something exact or close enough and I can mill out the rest. I don't think it has to be exactly the same length and width as the block below it.



https://www.ebay.com/itm/THICK-Stee...:USPSPriorityMailSmallFlatRateBox!72764!US!-1


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## WarrenP (Aug 17, 2018)

It is to bad you need it 1 5/8 inch thick. I have some 1 3/8 inch thick stock I could cut and send but guess it wont help. Sorry. Warren


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## savarin (Aug 17, 2018)

Heres my example. Simple to build and the huge increase in rigidity is well worth it.
Thread cutting at 90' is not a reason to hold back.
I only replace the compound when I need small tapers.
https://www.hobby-machinist.com/threads/plinth-for-qctp-on-9-x-20-lathe.45628/
Go for it you wont be sorry


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## Pcmaker (Aug 19, 2018)

TerryH said:


> https://www.ebay.com/itm/THICK-Stee...:USPSPriorityMailSmallFlatRateBox!72764!US!-1



Thanks, I just ordered it. Now for the planning on how to do this...


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## TerryH (Aug 19, 2018)

Pcmaker said:


> Thanks, I just ordered it. Now for the planning on how to do this...



You're welcome. I found it when I was searching for material for mine and had it in my watch list. I'm basically following the way Mike Higgins did his in the video I linked. Pretty simple matter of drilling and tapping once the piece is cut to size. It'll be nice that you can do yours with a single piece of plate. Little more to it for me on the G0752 because I couldn't find a piece of plate thick enough to get the tool height I needed. I have a 1" piece for the base and a 3/4" piece on top of that for the QCTP.


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## ttabbal (Aug 19, 2018)

I couldn't find steel for a decent price, so I'm trying some Fortal aluminum, which looks to be a type of 7075. On the up side, it's a lot lighter.. I'm not convinced on threads in it, so I might have to sink a steel plate in it or something like that. Mostly it's just a spacer with through holes, so it should be fine. If I don't like it I have some stock I can make a 2 part steel version with.


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## TerryH (Aug 19, 2018)

ttabbal said:


> I couldn't find steel for a decent price, so I'm trying some Fortal aluminum, which looks to be a type of 7075. On the up side, it's a lot lighter.. I'm not convinced on threads in it, so I might have to sink a steel plate in it or something like that. Mostly it's just a spacer with through holes, so it should be fine. If I don't like it I have some stock I can make a 2 part steel version with.



I really wanted a single piece but needed 1 3/4" minimum to get tool height and at least 4 3/4" x 3 3/4" to match the Belfanti 6 bolt conversion for the G0572. Couldn't find such even though I figure it's out there  somewhere, just no where I could locate. I ordered the pieces cut to proper size (1" - 4 3/4 x 3 3/4 and 3/4" 3 x 3) from Online metals for $27.74.


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## MSD0 (Aug 20, 2018)

Pcmaker said:


> I've read a few times in this forum that some posters got rid of their compound slides on their mini lathes. Apparently, it makes it more ridgid for parting off.
> 
> I'm thinking of doing the same thing. What are the pros and cons? So far, I haven't really had the need to use the compound and it's very hard to part off because of ridgidity problems on my 7x12. Do I just drill and tap the cross slide for the QCTP bolt?


Made a solid tool post for my PM1127. Parting is really easy now.


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