Issue with tool rest

[Burlhunter]

I would not want to guess how many versions of this part there have been in the 60+ years the system has been in production. Two minimum, but probably more. IMO, the rack type is better than the spiral type because 1) it locks to the carriage better, and 2) if it is not locked solidly to the carriage it won't turn very far. I measured one at 8". That is a bit longer than the spiral type I have, and which I can't measure because that design is integrated with the tool rest arm and not easily separated. If I had the equipment and was making my own, I would make it the length of a main table leg because I'd find other uses for it. (And as you point out, too long is not an issue.)

I didn't understand the countersink reference but I agree you should not use an extension table leg for this. They do not have the wall thickness for the rack.

Ed beat me with the pics but confirms the 8" measurement. I'd still go 14 or 15". I have a few extra main table legs around and find uses for them regularly.

- David

Theres 2 for sure that I know of. 3 if the 10er is different but I haven't looked at them at all. But from my findings theres one that comes from the mk5 500 that's threaded and I believe at the 510 they go to the side spline kind through to the mk7. But its really hard to tell to be honest .

[Burlhunter]

I would not want to guess how many versions of this part there have been in the 60+ years the system has been in production. Two minimum, but probably more. IMO, the rack type is better than the spiral type because 1) it locks to the carriage better, and 2) if it is not locked solidly to the carriage it won't turn very far. I measured one at 8". That is a bit longer than the spiral type I have, and which I can't measure because that design is integrated with the tool rest arm and not easily separated. If I had the equipment and was making my own, I would make it the length of a main table leg because I'd find other uses for it. (And as you point out, too long is not an issue.)

I didn't understand the countersink reference but I agree you should not use an extension table leg for this. They do not have the wall thickness for the rack.

Ed beat me with the pics but confirms the 8" measurement. I'd still go 14 or 15". I have a few extra main table legs around and find uses for them regularly.

- David

Sorry for the double reply but i forgot to type this trying to do this and listen to my wife say something and hit send lol. But by countersink I meant the groove the set screw goes in to lock it down and keep it from slipping up and down once locked. I should have said groove or step down width, you'd probably caught it right off then so thats a my bad. But yeah, to long is ok, but to short not so much lol. I wouldn't trust a leg either tho for exactly that reason to, it would work, but why risk it. I ended up cutting a 12 inch piece of 1-1/4 solid aluminum bar stock and used an 8tpi die and cut threads into all of it but the last 2 inch and turned an 1/8 deep 3/8 inch wide groove for the set screw to seat into and it works great. I found an old bed wheel/handle off an old Bridgeport mill and it just so happened to have a 5/8 hole and went right on where the lever turns it up and down so that made it easier to adjust the tool height. Moves really nice like that but it sticks out the bottom visually further than it should but ahhh, im ok with that lol. Still thinking about using this 48 inch acme thread I have and putting a worm feed on it tho haha. That would be neat as can be I think if it had an automated carriage with a switch in the headstock to move the carriage back and forth lol. Its dumb really, but you gotta admit, it would definitely be cool lol. Put a little cheap digital read out on top of the power head that read out how far the center of the 2 saddle holes are from the headstock spindle and be able to zero it lol. I bet you could even retrofit a metal lathe saddle post on it and set the tool so all you had to do was hold the switch and it would make a cut like a metal lathe turning a long journal . Idea's Idea's lol.

[RFGuy]

The Shopsmith mk5 500 tool rest post is threaded, it doesn't have concentric rings at all. Its 1-1/4 8tpi thread. The table legs like in that one picture above is splined on one side to mimic the action of threads so it can move it up or down. But I assure you, the original factory SS mk5 500 tool rest post is threaded, mk5 520 and mk7 use the one side spline to drive it up and down tho. The logic in doing it myself is simply because I can, no more no less. Sure, I could jump on ebay right now and grab one for 20 bucks, but really, whats the fun in that? I didn't learn how to do this stuff to buy it from somewhere else, I learned it so I could do it myself lol. If I knew how to add a picture on here I'd show you a picture of one zoomed in on the last thread where you can see it tapering away and how the last couple are flat from not totally going through the die before being backed off, but thats definitely threads and not concentric rings. Nonetheless, I finely figured out how long it was anyway. saw a picture of one beside an 8 inch rest so I screenshot it and blew it up till it was the correct scale and presto, I got the measurement for the post lol.

What??? Have you looked at the carriage the tool rest feeds into? Together they make a rack and pinion. The tool rest post is NOT threaded and a threaded post won't work in the carriage. The guys who replied to your post are very experienced and know what they are talking about so please don't summarily dismiss what they say. For help on how to post a picture please refer to the thread linked below:

viewtopic.php?f=7&t=19246

[rpd]

Since the last PHPbbs upgrade, you can just drag and drop the photo onto the message, which downloads it, then put the cursor where you want it in the message and then click the "Place inline" button. Easy Peasy.

[Burlhunter]

The Shopsmith mk5 500 tool rest post is threaded, it doesn't have concentric rings at all. Its 1-1/4 8tpi thread. The table legs like in that one picture above is splined on one side to mimic the action of threads so it can move it up or down. But I assure you, the original factory SS mk5 500 tool rest post is threaded, mk5 520 and mk7 use the one side spline to drive it up and down tho. The logic in doing it myself is simply because I can, no more no less. Sure, I could jump on ebay right now and grab one for 20 bucks, but really, whats the fun in that? I didn't learn how to do this stuff to buy it from somewhere else, I learned it so I could do it myself lol. If I knew how to add a picture on here I'd show you a picture of one zoomed in on the last thread where you can see it tapering away and how the last couple are flat from not totally going through the die before being backed off, but thats definitely threads and not concentric rings. Nonetheless, I finely figured out how long it was anyway. saw a picture of one beside an 8 inch rest so I screenshot it and blew it up till it was the correct scale and presto, I got the measurement for the post lol.

What??? Have you looked at the carriage the tool rest feeds into? Together they make a rack and pinion. The tool rest post is NOT threaded and a threaded post won't work in the carriage. The guys who replied to your post are very experienced and know what they are talking about so please don't summarily dismiss what they say. For help on how to post a picture please refer to the thread linked below:

viewtopic.php?f=7&t=19246

Odd then how a 1-1/4 8tpi nut* will screw right up it then I guess. Im telling you, its threaded, and this isn't the first time this has been brought up, but in others threads (no pun intended). If you pull an old style post out of the carriage of the mk5 500 model and look at it you will clearly see that its threaded. Obviously if its a newer one with the single side spline then its not, but the original mk5 500 models are definitely threaded without any doubt. Hopefully those pics i just added work cause they show the difference between the 2 different post styles between older and newer, threaded and splined.

[Burlhunter]

Since the last PHPbbs upgrade, you can just drag and drop the photo onto the message, which downloads it, then put the cursor where you want it in the message and then click the "Place inline" button. Easy Peasy.

Hey! thanks for that, ive been on my phone and its hard to see it all at once lol. I kept hitting the little photo icon on top where all the emojis are and it wouldn't do anything lol. So yeah, thanks for steering me in the right direction !!

[reible]

Well it looks like I was wrong. Pretty clear from the pictures that it is a thread. Sorry.

I did have one or more of those over the years but much much prefer the newer design. Those old ones were hard to clamp in place and liked to twist. The new one does too but to a much less extent and you can get rid of a lot of that by where you locate things.

So now the question, why did they do that threading, cheaper because it was faster or something? I did check the new one and it is not threaded, just a square against the shaft shows they are not. The gear that this runs against is also not a pitched affair. I guess the engagement is able to deal with this fact but this might also lead to the easy to twist stem issue. Anyone have any incites to this?

Wants it warms up I will try and locate one of my old stems and do a side by side compare for my own knowledge, unless someone would care to do that before then.

Ed

[DLB]

So now the question, why did they do that threading, cheaper because it was faster or something?

Maybe a bit of logic, but not a complete answer. On my old Greenie version the arm is not removable from the post. So it pretty much has to rotate at the carriage in order to function. Later they made the arm removable, which added a pivot point, so on that version is a complete mystery to me why they did not go to the rack type post. I'm with you though, I don't like them. You really have to gorilla the lift lock on the carriage to keep them from rotating.

- David

[JPG]

Somewhere the notion of 'normal' gearing mated to a non-matching notched/threaded movable object crept into the minds of SS engineers. Cases in point tool rest post and speed control.

For sure the quadrant is produced much cheaper with the straight 'teeth' than if it were made with a concave surface matching the worm gear.

Likely the same(cheaper) re the original tool rest post.

Both suffer from minimal contact area. The current tool rest still has minimal area with the pinion gear mating with the flat(although better than mating with the round tube).

The original tool rest post also suffered from the pinion gear only contacting the thread 'peaks'.


Original as in M5, nit "10E".