Vintage Machinist's Stool - Needs Help

[mark-NJ]

My daughter's store is remodeling, so lots of stuff is dumpster bound. She called to ask if I wanted an old stool for the shop, and I said "sure...why not?"

This is an older screw-jack model with a lot of paint and a really bad wobble. I suspect there's some missing pieces:




The screw is a.) loose in the threaded height-adjustment "wheel" and b.) in the sleeve that it passes through. There's like 0.060" slop, so the entire top wobbles badly. The threads are worn, so the height-adjustment "wheel" is not at all tight...




My aim would be "functional", not restoration (although I don't rule that out). To that functional end, I thought I could just remove this screw, replace it with a 1" threaded rod and weld companion nuts to the top & bottom of the tube on the chair frame, but I'll be darned if I can get the old screw out. And the piece that it's into looks like a casting, so I'd rather not break it (although it's already broken on one of the 4 arms).



And I suspect that there should have been "something"...maybe a sleeve of some sort... that makes everything A-OK, because the adjustment wheel has been grinding into the top of the stand for a log time now...




So...

1.) any idea what I've got here? Venture a guess at the age?
2.) any idea if the wobble is due to missing parts, or if it's just years of wear?
3.) any idea what that thread (dia / pitch) is? A nut welded (or brazed...it might be a casting) to the bottom of the tube would solve a lot of wobble issues.
4.) any idea how the screw can be removed from the seat-support casting?

Thanks for looking!

 

[Provincial]

That may be a repurposed piano stool. Most were wood, so someone built the metal frame. I think that you are right about parts being missing. They may not have been there when the metal frame was built.

 

[The Cobbler]

My grandfather had one similar at his workbench, he passed in 1972 . I remember it was a bit wobbly too . it's acme or square thread probably . must have a peen or something holding it to the bracket . looks like a bracket riveted to the arms, maybe something between the 2 pcs holding the screw in place . you can probably get acme thread stock & a nut from Macmaster CArr

 

[Mintgrun]

I'm guessing most of the wobble is happening where the acme thread is passing through the tube underneath the height adjustment "nut". If that is the case, I'd be looking for a plastic sleeve to go inside that tube and provide just enough clearance for the threaded shaft to pass through. Ideally, it would have a flange on the end to eliminate that metal on metal contact, but adding a large (plastic?) washer there might also do the trick. Shopping for new Acme thread/nut will be expensive and getting the old one out seems a bit involved. Sometimes a little wobble just adds character.

 

[mark-NJ]

Yes....the wobble is because of the slop between the screw & the tube at its base. A sleeve / shim is a great idea, but it's an odd ID & OD and needs a wall of about 0.030" ....I've searched and found nothing. I don't have a lathe or I'd make one...

Assuming the screw is Acme 1-4 (which is my best guess...haven't measured anything yet), I can get a steel nut for about $8 bucks and TIG it to the bottom of the tube. That alone ought to solve everything.

The wobble exceeds the definition of "character"...

 

[Provincial]

Those don't look like Acme threads. They look like square threads. Acme threads have a 29 degree angle.

Acme Thread

Square Thread

 

[mark-NJ]

I took a deeper look this evening...there's a taper to the threads, so it's an Acme, not a square...although some sure look square from being so badly worn. There's 4 TPI...and while that appears to be a less-than-common pitch, McMaster has 1"-4 nuts for $7 bucks each, so worst case I'm out $14 (plus S&H ). We'll see if they work in a few days.

 

[Provincial]

Make sure it isn't double-lead threads! They move twice as fast. A 2 tpi double thread looks like a 4 tpi regular thread.

 

[mark-NJ]

Doesn't look double to me...what do you think? (I'm not experienced with these big threads).

Anyway, nuts are on order, and it's a binary proposition: they're either right or they're not.

 

[leg17]

Not a double pitch thread.
Is that bracket actually a stamping?
If you are going to use two separate nuts, they will need to be 'synchronized' in some way.

 

[mark-NJ]

1.) thank you
2.) the bracket is a casting with 4 stampings riveted to it.
3.) I bought 2...one for the tube's bottom + a spare. But sync'ing them is pretty easily done if I decide to put them both on the tube (top & bottom).

 

[mark-NJ]

Well, I got my nuts.

I don't know what that shaft IS, but I surely know what it ISN'T: it ain't Acme 1"-4. But there is a solution: I just bought a 12" long Acme 1"-4 rod. Since the original rod is badly worn and since the seat mount bracket is broken anyway, I'll just make a new plate for the seat and weld the new shaft to it.

This stool will be great & will get another 75 years of use! Pics to follow...stay tuned!

 

[bugnut]

Mark, i am late to the party but your fix will work. I believe the original had a bearing in the groove on you second picture. At some time in its life it expired and was never replaced.

 

[mark-NJ]

Well, no time like the present, right? My screw came today, so I dove right in.

The screw slid in nicely, so I put on a top nut and TIG'd it in place. Burned some paint, but the rod threads in & out nicely:







I set the bottom nut carefully; it had to be sync'd congruently with the top nut or the shaft would be locked in place. I snugged it up to the bottom of the tube, then backed it off a smidge, verifying that the rod turned freely. I held the nut in place and TIG'd a spot.

I was concerned that a full-around TIG weld could thermally distort the nut to the point of jamming the shaft, so unlike the top nut, I didn't use any filler rod, preferring to just make a few autogenous weld points, keeping the heating of the nut to a minimum. After all, this nut is only there to provide stability to the seat to prevent any wobble. A couple of generous-sized spots, and it's not going anywhere.




What's this? An apple pie cooling? Nope, that's the bottom of the seat having had 3 coats of paint removed, and now it's down to the prime. I'm not "there" yet, but it looks like this might be a nice piece of hardwood. I cant wait to sand, stain & wax it!



Stay tuned...more to follow.

 

[mark-NJ]

All the old finish on the top is off. It seems almost too good to be true, but the top isn't just some unidentifiable hardwood, but it's maple...in fact, it's flame maple!

Sadly, the previous owner re-attached it with some through-bolts, the holes for which needed to be drilled out & doweled. Happily I had some scrap maple in the bin, so I cut some plugs and glued them in.




I cut up some scrap steel and TIG'g up a support plate. Funny how fast post-welded steel begins to oxidize. I'll hit this with some paint later today.



Some stain, and the grain & flame in the this top really jumps!



...and now, sitting on the plate (but not attached yet) with 2 coats of BLO. NIce! A couple more coats, let the wood drink it up, then I'll give it a rubbed wax final.



The top was hideous with that blue paint...it had to be refinished, and I think the wood looks nicer now. But the rest of it? I was going to take it to work, sandblast it, then paint it, but I'm now thinking that the old chipped blue paint has character and speaks to a century of (ab?)use...

What do you think? Refin the metal, or leave it as-is?

 

[matthew]

I like character… but the maple is beautiful, and it looks a tad distracting from the maple. I’d probably go flat black, so it looks more like vintage cast iron to complement the vintage maple.

Is it riveted together? I’m wondering if it could be broken down into small enough pieces to heat and oil quench for the oil blued look (like seasoned cast).

 

[RTM]

I would definitely keep the metal as is. Once your **** starts polishing that flamed maple with use it's going to look even more fantastic.

 

[The Cobbler]

that's a great looking pc of nostalgia you have there, and a great fix too!

 

[Mintgrun]

I’d probably go flat black

I would definitely keep the metal as is

I would paint the raw nuts/welds black and leave the rest as is.

 

[SweetD]

Great project, thanks for sharing! I'd love to find something similar here locally.

 

[steel 35]

Great Jack’s

Forgot where mine was, for a minute and it’s black.

 

[mark-NJ]

The welded seat bracket has been painted black. I'll hit the nuts with some paint, too.

There's another thread where I discussed the workshop that I'm gutting & rebuilding at our cottage in Maine. I've decided that this stool, as-is, is going to be the bench stool for that new shop. I think it will be the perfect compliment to the bench I'm building.

This piece had outlived (what was thought to be) its usefullness and was serving as a window theme display piece in a women's clothing store in a Paramus, NJ shopping mall. Next stop was a dumpster > landfill. I'm thrilled to have been able to save it and give it a new lease on life! Recycle > refurbish > reuse...lovin' it!