Techno Isel Lathe Refit Using Centroid Acorn and Teknic Clearpath Drives

Post your completed retrofits for the world to see.

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Reedfirst
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Re: Techno Isel Lathe Refit Using Centroid Acorn and Teknic Clearpath Drives

Post by Reedfirst »

MecTechMike wrote: Thu Jul 11, 2019 9:35 pm Adam,

I am interested in seeing your linear rail and gib solutios for your lathe. Got pictures or videos you posted?

Mike
Mike, sorry I missed your post asking for a few pictures.

Here are some pictures of my tapered saddle gib solution
IMG_20190602_091207_194.jpg
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Re: Techno Isel Lathe Refit Using Centroid Acorn and Teknic Clearpath Drives

Post by Reedfirst »

15633165506306697808619557517170.jpg
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Re: Techno Isel Lathe Refit Using Centroid Acorn and Teknic Clearpath Drives

Post by Reedfirst »

15633167304663493749249553931816.jpg
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Re: Techno Isel Lathe Refit Using Centroid Acorn and Teknic Clearpath Drives

Post by Reedfirst »

15633168175855601163910060461284.jpg
ScotY
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Re: Techno Isel Lathe Refit Using Centroid Acorn and Teknic Clearpath Drives

Post by ScotY »

Hi Reedfirst,
Do you have any more pics or info on how you did those mods? I have a different lathe and I’m looking for ideas. Looks nicely done, btw!
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Re: Techno Isel Lathe Refit Using Centroid Acorn and Teknic Clearpath Drives

Post by Reedfirst »

ScotY wrote: Sun Jul 21, 2019 3:56 am Hi Reedfirst,
Do you have any more pics or info on how you did those mods? I have a different lathe and I’m looking for ideas. Looks nicely done, btw!
The tapered gib blocks are machined out of aluminum and bolt to the underside of the saddle. The original gibs were made of steel bar stock and utilized copper crush washers to take up the slack between the gib strip and the bottom of the saddle. Previously, it was practically impossible to adjust the slack out of the saddle to bed without getting either a tremendous amount of binding or slop in the saddle.

The blocks I machined have a taper in them where the delrin gib slides upon. I was (am) still learning fusion 360 cad/cam and was struggling with programming the cam to cut the taper so I ended up using a 1degree angle block to cut the taper in the slot of the aluminum block. The delrin gib was machined out of a piece of 1/2 delrin plate that I first cut out on my table saw and then machined on the mill and finally lapped the width of the gib on my surface plate for a tight sliding fit within the block. To figure out the height of the delrin gib I simply bolted the blocks to the saddle and stacked feeler gauges between the gib block and the bottom of the bed to figure out how high i wanted the gib to be above the gib block. I subtracted a couple of thousandths and machined the final height of the gib with it super glued into the adjustment block. This in effect transfers the angle from the adjusting block to the gib strip. The gib is then carefully released from the super glue and turned end to end so the gibs taper and the taper in the adjustment block work with each other.

If you notice, on the ends of the gib retaining blocks there are two adjusting screws. These are just regular socket head cap screws that I attached a turned piece of steel and pressed them onto the screws with some green loctite. Tightening one side of the adjustment block causes the gib strip to raise in a parallel orientation and the opposite adjusting screw traps the gib from going too far.

I was and am still very new to fusion360 and cad/cam. So please don't be to harsh with my elementary drawings. However, if anyone wants them Here are the dxf files for the front and rear gib blocks I made. I can't guarantee that they'll fit another techno lathe perfectly (I'd double check the dimensions) but it may help someone making a set for themselves.

https://www.dropbox.com/sh/rj3ptqcu0ock ... 0HJfa?dl=0
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Re: Techno Isel Lathe Refit Using Centroid Acorn and Teknic Clearpath Drives

Post by ScotY »

Thanks, Reed! I was wondering what you made the gibs from...now I know. I understand how you made them and the mounting blocks. How did you do the linear rails? Can you post more pics?
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Re: Techno Isel Lathe Refit Using Centroid Acorn and Teknic Clearpath Drives

Post by MecTechMike »

Nice work on the linear rails and tapered gib for the saddle. Very nice.

I agree that the original plate with spring copper washers to set the tension force has a lot to be desired. You've given me a new project.
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Re: Techno Isel Lathe Refit Using Centroid Acorn and Teknic Clearpath Drives

Post by Reedfirst »

ScotY wrote: Mon Jul 22, 2019 8:41 pm Thanks, Reed! I was wondering what you made the gibs from...now I know. I understand how you made them and the mounting blocks. How did you do the linear rails? Can you post more pics?

The design of my linear rails are a direct result of what I had on hand and was really intended as an experiment..... :lol:

The reason I went with linear rails was because the cross slide to saddle fitment was really far off. I believe when Techno-Isel was producing these machines they took the cross slide off and flipped it around so the gib adjusting screws are on the opposite sides as there were from the factory. They did this so the mounting screws for the ball screw block wouldn't interfere with the gib. I originally was going to re-scrape the cross slide to the saddle but after some checks with I found my cross slide was warped and the dimensions of the dovetail were pretty far off. Not to say it couldn't have been repaired but I wanted to give the linear rails a shot as I have never worked with them before.

To mount the rails, I first took a piece of precision ground shaft (thompson linear shafting) and clamped it into the "V" way in the bottom of the saddle. I then mounted the saddle on parallels onto my mills table and used a test indicator to sweep along the precision shafting to indicate the saddle square to the x travel of my table.

I wrote a simple program in intercon to drill the holes for the mounting screws for the rails and tapped them for m4 threads.

To align the rails to the spindle axis I mounted the rail that was closest to the head stock onto the saddle and placed a test indicator mounted to a magnetic holder on top of the rail truck. I then put a parallel against the chuck body and lightly clamped the parallel with the chuck jaws. To verify the parallel was square, I set my test indicator to read "0" on one end of the parallel and spun the chuck 180 degrees and adjusted the parallel until both readings on each end of the parallel read "0"

I then swept the test indicator across the whole length of the parallel by moving the rail truck along the length of the linear rail until I was happy with the reading. I think I set it so there was about a tenth of taper moving toward the center of the spindle axis. I then mounted the other rail and swept that one in with my test indicator using the first rail as its reference.

All in all it works pretty well. I get a decent finish on aluminum and threading seems to come out pretty good. I do get some chatter when parting however, my parting blade isn't much to be desired.

I've been thinking about re configuring the linear rail design to incorporate 4 trucks for more rigidity. I've been toying the idea of machining off the dovetails on the saddle, filling the void with epoxy granite and mounting the trucks to the saddle and the rails to the cross slide or making a seperate linear stage using low profile hiwin mgn15 style linear rail and trucks that bolts to the saddle as an assembly.
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Re: Techno Isel Lathe Refit Using Centroid Acorn and Teknic Clearpath Drives

Post by Reedfirst »

Also, another possible modification I'd like to experiment with in the future is to try applying moglice to the underside of the saddle to improve the saddle to bed fitment and also add some sort of oiling system for the saddle.
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