Draw tube liners

Ok, I give up. Trying to find a convenient but effective way to line the inside of the draw tube on a Haas Lathe. Here's what Ive tried so far. A lite press fit with plastic bushings tapped into the draw tube. One near the front, and one near the back. Works pretty good but when the spindle is warm and you want to change them, they have expanded a little too much and are a beast to pound out of there.
Next idea was a plastic bushing that is a slip fit but cut a O ring groove in it. The O ring creates a drag on the I.D. of the draw tube to help it stay in place. Problem: Certain areas of the draw tube have a gap for it to draw in and out for closing and opening the chuck. The O rings get stuck in the gap and once again, a beast to pound out.
Third Idea: An aluminum sleeve turned to a slip fit for the draw tube. Aluminum sleeve has a plunger type set screw in it that makes the spring loaded plunger put pressure on the bar. Only need one sleeve that goes on the end of the bar and follows the bar all the way through to the front of the collet. Problem: the plunger does not put enough pressure on the bar, and falls off the bar half the time.
There has to be some good ideas out there for this. You guys got any?

hi dave i use the same last method you use and it works fine for me ,what size ball plunger do you use,maybe its to small i use a 3/8-16 ball plunger,have you tried adding a 2nd ball plunger to the collar.

I made the alum sleeve and crimped the end near the chuck. Sleeve can be pushed in farly easily.

I then made up a bunch of poly adapters which float freely thru the tube and snug to the barstock, some have nylon setscrews to add tension to the bar yet allow to be pulled.

Push tube in, select adapter, slide on bur free stock, adjust tension if needed and slide inside machine. Adapter slides up to crimped end of tube and allows bar to continue to be fed all the way to the end.

chas,
I still like this idea and would still like to pursue this method. I am using 1/4 setscrews for this. I would like to use bigger ones but here's another problem with this method. The I.D. of my draw tube is 1.81 dia. If I am running barstock of 1.25 dia. the wall thicknes of the bushing is about .28. Most set screws with the spring loaded plungers are going to be too long to allow the collar to fit in the draw tube. So what do you do in that case?

most of the jobs i do are less than 1.00 dia so the 3/8 ball plungers work fine for me. have you checked with haas about buying a spindle liner.

Hey Dave,
I have made adapters before but connected and made them a little different. On the back of your actuating cylinder there is normally a plate that can be taken off for barfeed apps. Fab up a flange that you screw tubes into with the same bolt pattern on it. You can buy synthetic tube stock in about any size you need, some machining may be required to get the I.D. of your draw tube. Thread the outside to screw into your flange. Screw it in, slide it in from the rear and bolt it up. This gives you a fairly flexible and somewhat quick-change design for change overs. I hope I explained myself well enough to get my point across ( just got a 12 hr night shift )and I hope this helps someone.

Dave

I made a "flange" like cncmek described. It has different liners I can put in to use whatever stock I want. My spindle bore is 2.5". So I can do a wider viariety of things for liners, but at the time that seemed the simplest.
Doug

Chas,
I checked with haas and all they sell is a piece of plastic to machine your own "donut" type bushing. Been there, done that.

cncmek and doug,
Hey, I like that idea!!! One question. What kind of liners do you use for the barstock. Are you talking about plastic tubing? If there is any machining to be done to them to accomodate bar stock size, how do you bore or drill them to the right size? I am imagining them to be at least 20 inches long. Unless I'm still not seeing it correctly. If you have a digital camera, a picture would be nice, but I think I get it.

Dave, I use standard pvc tubing, and some other types I get from Boedecker in various inner dia.'s. I really don't machine the id. I just get close to the right dia. As long as there is not too much movement, than I don't have any problems. Mostly I will run 1" dia, and 1.5-1.75. Pipes come close to that. As long as the bar can't swing too far off center, my parts come out great. IE 1.55 Id ect...for a 1.500 bar dia.
I had originally thought about boring out all of the pipes to exacting tolerances, but I got lazy, and the jobs needed to run.
So of to the races I went.

Modular Machinable Draw Tube Liner

Old post I just found. I have been using these liners they come to fit certain machines but do not come bored. They come in short sections so they can easily be bored out to what ever stock you have and or what kind of fit you want then you just have to snap them together.

eduarte said:

Old post I just found. I have been using these liners they come to fit certain machines but do not come bored. They come in short sections so they can easily be bored out to what ever stock you have and or what kind of fit you want then you just have to snap them together.

View attachment 254106View attachment 254107

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What brand are they/where do you get them?

barbter said:

Dave - what is your plastic?
Nylon is the worst as it absorbs water massively (hygroscopic).
You need to use Acetal or Delrin type mtl to stop a lot of the "swelling"

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Barbter,

Have a look at Dave's post date.... 2004.
I hope he delivered the parts by now.