9" SM Utilathe Restoration

[PeterT]

I just realized looking at your parting assembly, that is probably the rear end of the blade sticking out, so disregard that part.

Agree with Craig, the riser block should be machined or at least very flat and parallel on both faces.

Two very quick setup checks you can/should do is using a typical 6" steel rule. Make sure you have at least a skim pass on work surfaces so they are true.
Centerline - lightly trap the ruler with the parting tool. The ruler should be straight up, not angled in or out. Adjust tool height as necessary. Other pic shows low tool height example
Parallel - put the rule contacting the end of the work and contacting the parting blade. Rotate & lock down the toolpost as necessary.

 

[francist]

I don't think I've seen a tool post rigged like that before. It's almost like two incarnations of something hanging off the side, one holding a parting tool attached to another which attaches to the tool post. That's a lot of lever advantage hanging off the side.

I would look at the spacer block as well as has been mentioned by Peter and Craig. If it's aluminum it can be a bit slippery on its own and not help matters. The old square of brown paper bag between mating surfaces does work and can help an otherwise borderline situation.

A deeper T-nut might be something to consider as well, the one in the photo doesn't look to be very thick. That in itself won't solve the entire problem, but I think it might give a little more purchase and not strip threads so easily. Just something to think about.

-frank

 

[YYCHM]

The tool holder is a bit of a contraption (it came with my mini lathe). With the cut off tool installed the blade sticks way out from the anchor point. Not only did it tend to spin, the height adjustable piece wanted to cock over. I broke the blade when I lowered it in order to eliminate the tendency to cock, so my fault entirely. A dull blade probably didn't help the situation. Can't really make the T-NUT any thicker. It's the same depth as the one that came with the lath, only that one is welded to the bolt.

 

[Johnwa]

I made a t-nut for my lathe out of a piece of ½ “ stock. You have to mill of the edges so it is an actual T. You get twice as many threads engaging.


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[YYCHM]

I made a t-nut for my lathe out of a piece of ½ “ stock. You have to mill of the edges so it is an actual T. You get twice as many threads engaging.


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Ok, I get it now. Makes sense.

Craig

 

[francist]

You can also make them on the lathe if no mill is available.

-frank

 

[PeterT]

What the guys are talking about is milling a T profile which would give the extra material shown in red. This gives more thread engagement.

But a 1/2" threaded post can hold a high amount of tension force. The usual thing you hear about with Gronk torquing is the cast iron goes 'tink' along the orange lines & then you have a cracked compound to deal with, so go careful there. The surfaces really do have to be flat good, but nothing you cant accomplish with basic machining & stroking it across some 600 paper on glass. A smooth mat finish. Also check the bottom of the tool post. If its Chinesium, chances are good it may not be flush. A bit of blue on either side & re tightening will tell you the story, particularly if this is the same tool post you will use for turning. The paper gasket is a good idea, but ideally yous shouldn't need it.

 

[PeterT]

I feel like I read about this exact same thing on another forum. There could be something to that blade holder. But in the mean time...

Green arrow - check that the corner of the slot for the blade does not have a slight radius from milling. The blade corner will not seat properly in this undesirable fillet & this acts as a pivot point rather than being mated flush on the inside blade face where it gets support. A better solution is an undercut, but that's another $ manufacturing step. Kind of like chamfering & de-burring.

Red profile - I know the wedge is popular & supposedly makes a better finish on one side of the parting slot. But as you are sorting out your issues I would make it square looking on end (just for 1/4" or so). Parting isn't a great way to finish a side at the best of times, but generally you need a rigid setup to use 'other' tip geometry. So 90-deg profile looking down at the tool, enter straight in & you should see a nice full width shaving come off.

How much blade stick out did you have when you tried it?

 

[PeterT]

I like these T-style parting blades. The HSS ones aren't much different cost than regular. They are simple to sharpen, just straight into the grinding wheel with sufficient rake clearance. The sharper the better. The fit most common parting blade holders but check yours first.

 

[PeterT]

Another common source of error for parting holders that have the positive rake angle built into the holder. You have your parting setup working perfectly. say its extended enough for 1/2" stock. Then you need to part some 1" stock. So you loosen the clamp & extend the blade a bit. Now it cuts like crap. Why? because now the tool tip has risen above the center line of the stock relative to where it was before & is probably now rubbing, not cutting on the edge. (Hence the ruler check I mentioned).

The reverse can also be true & this can get exciting because the tool is below center axis & prone to digging into the work. Particularly bad on gummier materials like aluminum. Something will have to give & usually the cheapest thing is your work if you are lucky.

 

[Hruul]

This the T-nut that i made for my lathe. Used the lathe to "square" up the metal that i had. Then cut the sides out with a hacksaw and filed till it fit. Not great but it works, didn't have access to a mill or milling on my lathe.

 

[YYCHM]

Well.... todays project was a tool post.

Took the better part of 8 hours to make.

Started off by PHS'ing off a 1 3/4" piece of the 2" X 2" square stock Janger sourced for our group buy (Thanks John).

Next, I squared the cut ends off with a fly cutter on my mini-mill. Geepers those things fling chips every where. I had chips in my shirt pockets, chips stuck to my eye glasses magnets, chips in my pant cuffs.

Next, I located and drilled the 3/8" center hole on the mini-mill.

With the post mounted on the lathe, I made a dimple on it with the tail stock live center. Now I know where the tool point should be.

Back at the mill, I located the dimple and offset by 0.5 of 3/8" and proceeded to mill a 3/8" slot 0.4" deep. That's 40 passes on a mini-mill at 0.01" per pass

Finishing, amounted to locating, drilling and taping the tool hold down screws.

Ya, 8 hours... efficient I am not..... BUT.... "locate" is a deceiving word in terms of tool changes and table traverses,
as is the term drill!!!

The ruler check.

 

[YYCHM]

Per johnwa's suggestion, I crafted an actual T-Nut to mount the tool post.

I drilled and taped the T-Nut for 75% thread engagement. Also, I used a cutdown carriage bolt as it appeared to
fit closer than ready rod which seems undersized some what.

 

[Brent H]

That's looking pretty beefy now!

 

[PeterT]

Does your compound have a gib lock on the other side? Something like this?

 

[Brent H]

The 9" utilathe has 4 set screws to set the gib clearance but there is no lock - flat gib with 4 detents to retain the screw ends

 

[Janger]

Well.... todays project was a tool post.


View attachment 6482

Took the better part of 8 hours to make.

Started off by PHS'ing off a 1 3/4" piece of the 2" X 2" square stock Janger sourced for our group buy (Thanks John).

Next, I squared the cut ends off with a fly cutter on my mini-mill. Geepers those things fling chips every where. I had chips in my shirt pockets, chips stuck to my eye glasses magnets, chips in my pant cuffs.

Next, I located and drilled the 3/8" center hole on the mini-mill.

With the post mounted on the lathe, I made a dimple on it with the tail stock live center. Now I know where the tool point should be.

Back at the mill, I located the dimple and offset by 0.5 of 3/8" and proceeded to mill a 3/8" slot 0.4" deep. That's 40 passes on a mini-mill at 0.01" per pass

Finishing, amounted to locating, drilling and taping the tool hold down screws.

Ya, 8 hours... efficient I am not..... BUT.... "locate" is a deceiving word in terms of tool changes and table traverses,
as is the term drill!!!

View attachment 6484

The ruler check.

awesome! Are you getting better results? The tool looks perhaps a tiny touch high.

 

[PeterT]

The 9" utilathe has 4 set screws to set the gib clearance but there is no lock - flat gib with 4 detents to retain the screw ends

Interesting. OK so that could be another source of slight movement drift in the overall tool holding assembly, although there isn't a lot you can do about it without modifying the compound by adding a lock (which I would research well before embarking on).

I was going to suggest rotating the compound to say 45-deg vs your current parallel to bed axis position to get more footprint area between compound & cross slide for rigidity. But if you cannot lock it, then 45 or more orientation would work against you because it will now find backlash movement between the lead screw & nut, worse that torque force across your dovetails as you have it now. But your carriage is locked during parting, riiiiight?

A lot of guys are removing their compound & slide & replacing with a beefy solid base, especially on smaller lathes. They claim more rigidity, better turning finish, better tolerance holding - all good things. Its on my list but, but involves some potential mods to the cross-slide too so I want to be sure.

Anyways, hope your parting goes better now. Keep us in the loop.

 

[YYCHM]

A lot of guys are removing their compound & slide & replacing with a beefy solid base, especially on smaller lathes. They claim more rigidity, better turning finish, better tolerance holding - all good things. Its on my list but, but involves some potential mods to the cross-slide too so I want to be sure.

I did that very thing on my mini-lathe.

Loved it. Not only was it more rigid but there was a lot more room to work with (space is tight on a mini). I hardly ever used the compound after making it. Not sure It can be done on my Utilathe without modifying the cross slide.

Truth be told, I've done lots of parting off in the past on my mini. Why all of a sudden things are going sideways on this Utilathe has me baffled. Maybe it does have something to do with the compound being in place? There is no means of locking it.

Won't be able to try parting off again until I mod the new tool post to accept the cut off tool. I did do some facing off with the new post and that went well.

 

[Dabbler]

Put an indicator base on the flatway of your lathe, and your point on your tool post. push and pull and see how much play you have. it will be a lot more than you think. then check the compound, the cross slide, etc. it may be that one fo your gibs needs adjusting. this is how you tell. (feeling the gibs isn't always diagnostic). This is how Bert taught me to get everything tight.

P.S. even after getting it all tight, there is always some movement. you can't get it all out.

I agree that substituting a solid block for the compound is very good at getting the most out of the smaller lathes.