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Comes down to accurately boring a long hole with a Criterion DBL-202B on a manual machine.

There are better, more rigid systems than the original Thomson round rod/ ballbushing version.

I understand that you are refurbing a legacy system that is complete, presumably once worked well, and may have other significance to you.
But don't consider the Thomson stuff as either ideal, or as some sort of benchmark for price. It's not used on machining centers, for instance. :)
No refurbing, just a little borrowing.
1. I removed four of theses Thomson guides from this wood mortise machine. There are four guides on this vertical plate.

DSC_1486.JPG

2. I used those four Thomson guides to design this wet cutting tile saw. With the internal bronze bushings the alignment is pretty hard
to get the table to slide smoothly for 25". So I started to think about using plastic. Remember there is going to be water and tile residue splashing about.

DSC_1479.JPG

3. The four Thomson guides are now back on the mortise machine. And that takes it to post 1.
Should I stay with two Thomsons or one long Thomson for the rail slides?

To bore the 1.25" diameter hole in the aluminum housing I think this would work:

Machine scrap aluminum piece to square and cut some slotted holes from the center to the middle of each side.
Attach scrap to face plate and turn true.
Bolt aluminum housing to face plate and use a long boring bar on a lathe.
(The wood piece is acting as the aluminum housing)

The 1" threaded face plate to 1" straight pipe is held in a collet. Has proved invaluable for some operations.

DSC_1490.JPG DSC_1491.JPG

4. Looking into designing a housing to hold 3 rolling wheels. The lower wheel will apply tension on the 3/4" bar. The wheels would be UHMW.
The top two wheels would be easy to mount on some block. It's the bottom wheel that has to apply tension. That is the hard part. The drawing
views are not the standard way. I forgot.

DSC_1492.JPG

I tried to avoid explaining the story behind the questions in post 1.
 
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Not sure i completely understand the question, we all imagine how "we" would build it....:)

Assuming the "tile saw" is for decorative ceramic home improvement project tiles and not silicon wafers....

Re: the aluminum housing: I would make it as long as you thought necessary, and only bore each end, perhaps 1" deep, for replaceable UHMW donuts. I would include the squeeze option (slot, clamp screw), for minor tweaking and holding power. I actually prefer phenolic, oiled after installation, though, but not sure how that behaves with off-&-on water exposure. IOW, canvas or linen phenolic is dead easy to hit tolerances. It also comes in tube or rod. Rolled, or centerless ground from flat sheet strips. (I buy various rolled tube & rod sizes for pool cue features)

An eccentric stud is the easiest way i use to provide minor center offset adjustments. But a stud can also have a flange for support and be designed to slide up and down in a slot.
I'd also be inclined to use Delrin (acetal) for the wheels, which is somewhat more stable to machine. Or rolled phenolic tube or rod.....

smt
 
This three bearing idea is in the right direction. Notice the free play in the finished part. Missed it by that much.


Two shoulder screws could be used for the V bearings. Those two shoulder screws could be turned with offset center.
That would let the bearing move in or out for adjustment. But the center line of the bearings would be different. Might still be ok.

 
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Still not reading your mind completely....
So the following might or might not have use for your app?

You are familiar with cam follower bearings? include a mounted small dia bearing on a stud. complete assembly usually cheaper than the parts.
Eccentric cam follower bearing includes the eccentric stud, for adjusting center distance or position within small increments.

Other useful parts are *stripper bolts*. All sorts of bearing, bushing, or self-bearing compatible dia x L shanks with stud and head all in one piece.
Designed for the stripper plate on metal die sets, but i find a better use is for all sorts of axles and pivots.

smt
 
Those cam follower bearing are not sealed from the elements.

I was thinking about making one from a SKF 6001-2RSJEM.
It is stamped made in India and it was new old stock 20 years ago. I checked stock and I have 16.
The ID is 12mm and should be big enough for a custom turned cam and screw.
The OD is 28mm and makes fitting three bearings with a mount a little challenge in the same space as a Thomson from the pictures.
I think I need a little help with eccentric parts. :dunce:

I would need 12 bearings. I should have invested in these heavily. I think they cost $1 each.

 
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Look at this picture. If there was a way to make the two bearings on the V adjustable?
The invert the picture and two bearings are underneath the rail. Adjust them upwards so they apply slight pressure to rail.
I'm also thinking about turning delrin tires for the bearings. Maybe .100 thick.

The movie result make a sloppy fit because all the three bearings are in a fixed position. :ack2:
 








 
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