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 ARCHIVED TOPIC: Needing a compound rest


Please note this is an archived topic, so it is locked and unable to be replied to. You may, however, start a new topic and refer to this topic with a link: http://www.banjohangout.org/archive/379949

Lemon Banjo and Supply - Posted - 12/20/2021:  17:43:19


I'd like to replace my old lantern post setup. I am looking for a compound rest sort of like this:





That I can outfit with a quick-change tool post kinda like this:





That I can mount on this setup:





The slide table I have mounted on here is one I bought from here.


Edited by - Lemon Banjo and Supply on 12/20/2021 20:01:17

Helix - Posted - 12/21/2021:  04:43:36


I see you are using a standard stationary tool, good job.



It would be very simple for you to hook up a 1/4" finish router and use a spinning tool on a spinning lathe.



I see that you use a glued on back plate. How do you remove the rim?

My inside collette has wooden posts with mountain bike innertube glued on.  I drill them off center so I can "CAM" them against the rim wall, tighter. 



That way , Hunter, you don't need to glue the base on. My old collette was plywood, now I have solid Cherry. 



You have the set up that uses only one cross slide, brilliant, way to go,  but you are probably getting chips instead of ribbons, right?  that's characteristic of brick rims. 


Edited by - Helix on 12/21/2021 04:51:23




RB3 - Posted - 12/21/2021:  07:26:51


I can't tell from your posting if you're asking a question, so I don't have an answer, but I will provide an observation about the setup in your photo.

If that's an 11" diameter rim, I estimate that the cutting edge of your tool bit is located at least 8" from the center line of your tool post. You're only cutting wood, but lack of rigidity is the bane of precision and consistency when using any kind of machine tool. Having long, cantilevered tool mounting arrangements is not the path to rigidity.

Every young man wants a long tool, but if you can't make it rigid, it won't do you much good.

Lemon Banjo and Supply - Posted - 12/21/2021:  08:03:08


quote:

Originally posted by RB3

I can't tell from your posting if you're asking a question, so I don't have an answer, but I will provide an observation about the setup in your photo.



If that's an 11" diameter rim, I estimate that the cutting edge of your tool bit is located at least 8" from the center line of your tool post. You're only cutting wood, but lack of rigidity is the bane of precision and consistency when using any kind of machine tool. Having long, cantilevered tool mounting arrangements is not the path to rigidity.



Every young man wants a long tool, but if you can't make it rigid, it won't do you much good.






I guess I was trying to ask a question, it just didn't come out very question-like. I'm trying to find a compound rest that I can mount on my current cross-slide table, and I'm wondering if anyone here knows where I can get one?



I just about fell off my chair laughing at that one!

Lemon Banjo and Supply - Posted - 12/21/2021:  08:12:37


quote:

Originally posted by Helix

I see you are using a standard stationary tool, good job.



It would be very simple for you to hook up a 1/4" finish router and use a spinning tool on a spinning lathe.



I see that you use a glued on back plate. How do you remove the rim?

My inside collette has wooden posts with mountain bike innertube glued on.  I drill them off center so I can "CAM" them against the rim wall, tighter. 



That way , Hunter, you don't need to glue the base on. My old collette was plywood, now I have solid Cherry. 



You have the set up that uses only one cross slide, brilliant, way to go,  but you are probably getting chips instead of ribbons, right?  that's characteristic of brick rims. 






Yeah, I put brown paper between the rim and back plate. Turned 5 rims that way so far. I need to overhaul my current system, because my bits have been really grabbing too much. Not long after I took the photo above, the bit grabbed the rim so hard that it ripped it off the back plate. Luckily no one was hurt, and the rim was not damaged. Someone with much more rim turning experience than me showed me a better bit to get. I plan on upgrading to that type of bit as soon as possible. 



The type of collet you are describing, is that like a Longworth chuck?



I'm not quite getting chips, but they're not long ribbons either. They're ribbons, but maybe only a few inches long at best.



 

mbanza - Posted - 12/21/2021:  10:27:22


You can find compound slides on EBay all day: ebay.com/sch/i.html?_from=R40&...&_sacat=0 . Another option is to buy one as parts from Grizzly or other suppliers.

I never liked the glue it or screw it to a back-plate technique, so I got this setup: pennstateind.com/store/CUG3418CCX.html
pennstateind.com/store/CRJA.html
pennstateind.com/store/CRJPIN3.html

This allows you to easily dis-mount and re-mount the work piece as needed, and contrary to what some folks will tell you, re-mounts can be done to an acceptable level of accuracy.

250gibson - Posted - 12/21/2021:  11:08:25


Quick question regarding both of the setups pictured. Don’t either if you use cages, especially turning a glued rim?

mbanza - Posted - 12/21/2021:  12:32:42


I stand to the side of the work piece, and use a shield, eye and ear protection. I pay extra attention to joint integrity and have never had one fail.

Lemon Banjo and Supply - Posted - 12/21/2021:  12:55:28


Does anyone have any experience with compound rests such as this one?



smithy.com/products/compound-a...357613121



CompoundAngleToolpost_ffac1a17-a241-4cb8-b02a-4aa56440f54e_1024x1024@2x.jpg?v=1621959715" />

Helix - Posted - 12/22/2021:  03:26:03


I have all the pieces and mounts for a stationary bit, I also have a boring bar.
I turned my first rims by hand. They are round and accurate.
Bearing chatter and tool chatter are things to look out for anytime.

Yes, I agree, the tool is too far from its base and it sounds like it flexed just enough to grab. I did this once and only once.
The chisel dropped to the base and broke, the rest of the rim took six months to find.

No, mine is not a Longworth because that uses two plates to give equally expanding jaws like the Nova chucks or Mbanza's
I tried just using one plate of the Longworth, they are easy to make. Then I went with straight slots, easier to center and re-center.
I ended up making a solid cherry plate that I turned on the lathe. I cut the circle with my bandsaw.

I know the brown paper trick, but I don't trust it. I don't like patching screw holes, so I have never used paper or screws
There is a point where you have to turn the rim around and re-center the rim, and my inside and outside homemade colletes do just fine.

Yes, resets can be accurate. Even different types of jaws can slightly distort the rim so that it snaps back into place after turning and gives you a less than round rim or two radii.

I have a real dial indicator for making my work more time consuming.


250gibson As noted, we stand to the side. I use my lowest speed and a finish router @ 20K rpm , so 40K cuts per minute w two blades.
My own rims are "Build-ups". No cage so far. Then I turn the lathe off and hand rotate the last "kiss cut." = No tool marks.

Lemon's rims are Layups where the grain is parallel to the surface of the head.
Please note in Hunters photo the beginning of the characteristic optical illusion where now rounded pieces look straight.

Your rims have how many bricks? The grain on laminated rims or lammies is all one grain run, so ribbons would be characteristic of those.
So your grain is changing direction twice for each brick, once rotating towards the tool and once away from the tool.
So short ribbons or chips is still safe and clean, no snagging.

There are people using as many as 10 bricks per tier, that's 30 where 4 of the available 6 sides are covered in glue, always horizontal grain.
they are tough rims and make a lot of music.


DRH - Posted - 12/22/2021:  15:29:14


quote:

Originally posted by Lemon Banjo and Supply

Does anyone have any experience with compound rests such as this one?



smithy.com/products/compound-a...357613121



CompoundAngleToolpost_ffac1a17-a241-4cb8-b02a-4aa56440f54e_1024x1024@2x.jpg?v=1621959715" />






Hunter;



I just sent off a response to this very question to a friend who does CNC retrofits.  My advice is to avoid it if at all possible.   The compound rest accounts for almost all rigidity problems (chattering, etc.) on manual lathes.  I occasionally remove the compound rest on my lathe when I need to improve finish.



Look up Swiss style turning machines and get an idea of how they mount the tooling.  Solid blocks dowelled and bolted directly to the cross slide are the way to go.  The only drawback is you lose the ability to cut a long taper or bevel.  Short bevels and radii can still be cut with a form tool.



If you don't want to drill holes in the cross slide just make an aluminum tool plate and bolt it to the T-slots in the slide.



I'm sorry if this sounds pessimistic.  Good judgement comes from experience.  Experience comes from bad judgement.  I'm an expert in bad judgement.

Helix - Posted - 12/22/2021:  15:56:42


Fun huh?

Happy Christmas

DRH - Posted - 12/23/2021:  13:58:59


I probably should have read the OP more carefully.

You can mount the quick change tool post directly to the cross slide without the compound. That's how it was done on all the old turret lathes. Worst case scenario is that you will have to make a base plate to mount it.

If you go with a QC post make sure you select the right size for your machine. Too big and you won't be able to get the tool down to the center line. Too small and you will be severely limited in tool selection.

I prefer the turret type holder shown in the top picture over the QC holders. The turret block can be locked at any angle. You can do this with a QC block but it's a lot more frustrating.

RBuddy - Posted - 12/25/2021:  21:26:41


I think Rockwell Delta used to make a compound cross slide for wood lathes. Several builders here over the years had and use them. Great for cutting a tapered rim or an angle at the top of the rim in the case of a "woody tone ring".



I have one and mounted to a cross slide table like yours it is right about perfect height on my lathe to put the cutter where I want it. There is nothing wrong with a lantern post and tool holder like yours, you are only cutting wood. You can get right, left and straight tool holders and they are fast to change. It's always better to try and keep the cutter as close to the holder as possible but even in metal work it is sometimes necessary to use a boring bar.



The double cross slide and the compound angle adjustment for the top slide and tool holder is a very versatile setup.



You have to be careful ordering so you end up with a combination that puts your cutter at the right height.



The compound cross slides come up on ebay once and a while.



Whatever slide that operates above the compound angle adjustment has to have enough travel to meet your needs when doing the taper cut, whether it is a taper on the whole rim or just an angle cut on top of the rim. Hope that makes sense to you but since you are asking about it I sense you've thought it through pretty well.


Edited by - RBuddy on 12/25/2021 21:30:39

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