• This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn more.
  • PLEASE: Read the FORUM RULES BEFORE registering!

4

[How do I?] How does one mount a large (heavy) cylinder on a lathe?

3
Like what you see?
Click here to donate to this forum and upgrade your account!
10

Bill Kahn

Active Member
Active Member
Joined
Mar 19, 2017
Messages
38
Likes
10
#1
I am having a blast with my new PM1030V lathe.

I have a puzzle...

It is a 1030. So, I guess I can machine a 10" diameter cylinder 30" long. Or at least approach those numbers.

I have a 4" diameter steel (sort of) cylinder 7" long. Heavy. I want to make a better cylinder from this stock. How hard could it be? Chuck it up and make sharf.

Well, my chuck with the outside jaws (the ones that grab by pushing out) can only grab a 3" cylinder on their inside. OK, switch over to the inside jaws. They can grab the 4" but less than a half inch of one end. (Remember, this stock is heavy--almost wanted to get out the shop crane to position it.). But, grabbing 1/2 ", even through everything is steel, and really tightening up the jaws--well it is crooked. Steady rest is too small to go around it. Follow rest doesn't support from the bottom. Tried to use the dead center on the tail stock.

OK, now the question--what sequence of adjustments does one do to get the mostly but only sort-of cylinder chucked up basically axially symmetric and ready to turn? I guessed at the center of the cylinder (the end has about 1/4" of gentle wave in it) for the dead center. Got a dimple there. Loosened chuck. Retightened. Clearly I was off of center. But wrongly located dimple was already there.

4-jaw chuck same problem. Face plate--ok, but how do you mount a 7" cylinder to it?

Any suggestions for a big heavy chunk of roundish steel like this?

-Bill
 
Last edited:

Bob La Londe

Active Member
Active Member
Joined
Apr 19, 2014
Messages
237
Likes
127
#2
You can very likely fit a larger chuck on your lathe. It might be harder finding a larger steady rest that fits, but you could mock one up out of a tree fork and a saw. I'm only half kidding. You can make a wooden V block that fits your lathe ways, and then and knock it over and shim it up until your indicated in pretty good. Tighten your lathe chuck, Drill your center whole, remove your v-block, and support your part for turning with your center. You may still get a little hour glassing in the middle. I don't really know how much it will sag under its own weight. A good place for precision shims is... Harbor Freight. I periodically stop by and buy half dozen packs of cheap feeler gages.
 

woodchucker

Active Member
Active Member
Joined
Nov 25, 2015
Messages
1,022
Likes
645
#3
so with the jaws grabbing from the outside you will need the tailstock.
So create a plug to fit into the tailstock end of the tube.
What you want to do is first machine a plug that looks like a hat.
Fit it nicely into the tube end. then create a lip to stop it from pushing in.
Reverse it, then face and center drill the lipped (brim) side.
Put it in the tube use your center to hold the tube in. you can now do any turning you need to the outside. The inside cannot be cut w/out a steady rest.
 

Bob La Londe

Active Member
Active Member
Joined
Apr 19, 2014
Messages
237
Likes
127
#4
I think he has a solid cylinder. A tube would be easier if only because its lighter.
 

Wreck™Wreck

Active User
H-M Supporter-Premium Member
Joined
Sep 29, 2014
Messages
1,918
Likes
1,463
#5
I hate to say it but soft jaws, one may hold diameters far larger then the chuck, a 4 jaw will as well. The limit is that the chuck jaws will hit the ways before the part when holding on the outside.
This is a 20" disk held in a 20" 4 jaw where the jaws just clear the ways.


Good Luck
 
Last edited:

Chipper5783

Active User
H-M Supporter-Premium Member
Joined
Sep 25, 2014
Messages
565
Likes
406
#6
With a 10x30 lathe, you cannot machine something that is remotely close to 10" dia x 30" long. First of all the cross slide gets in the way, that takes you down to about 7" diameter. The 30" is the absolute max length between center points (no chuck, no ball bearing center), in practical terms you are down to about 24" working length.

You should have no trouble working a piece of 4" diameter bar 7" long. That is a robust piece of material, but strictly speaking, it is nothing special. You will absolutely need tailstock support. You need to get a center drill into the one end - but don't try that in the lathe. There is nothing wrong with just carefully laying out the center (measuring tools) and drill the center with a drill press - even by hand held drill. Of course, do as good a job as you can, but it does not need to be perfect. With a big hammer / center punch - you can migrate that mark you have until it is pretty close.

What chuck? It doesn't really matter. A half inch of grab is plenty (when the outer end is supported). Select a chuck and jaw combination so that the jaws are not sticking out past the body of the chuck (or if they must then as little stick out as possible - this is a safety issue and obviously stronger if they don't stick out).

Keep your speed down: 4" diameter - 100 rpm gives you 100 feet per minute, which for HSS cutting steel is about as fast as you ought to go.

Let us know how you make out. Regards, David
 

Bill W.

H-M Supporter - Premium Member
H-M Supporter-Premium Member
Joined
Jan 28, 2016
Messages
104
Likes
77
#7
I hate to say it but soft jaws, one may hold diameters far larger then the chuck, a 4 jaw will as well. The limit is that the chuck jaws will hit the ways before the part when holding on the outside.
This is a 20" disk held in a 20" 4 jaw where the jaws just clear the ways.


Good Luck
Wreck... What is the red thing in the picture? BW
 

Wreck™Wreck

Active User
H-M Supporter-Premium Member
Joined
Sep 29, 2014
Messages
1,918
Likes
1,463
#8
Helps keep the coolant in the machine, a 20" jawed chuck will fling coolant everywhere even at 250 Rpm's.
This is one of the advantages of a collet chuck, no jaws to turn it into a fan (-:
 

Silverbullet

Active Member
Active Member
Joined
May 4, 2015
Messages
2,357
Likes
1,062
#9
The problem you have is the reason when I'm asked . I say get the biggest lathe you can fit and afford. Small lathe equals small work. A lot can be done on your lathe the possibilities are as good as you are. But trying to build cannon barrels on a lathe made for 45-70 barrel. And that would be pushing it. Run your lathe build some projects and tools have fun learning from your lathe. Good luck with all the future builds. Just share is what we like. Pictures and more. Ck marks builds on here if you want inspiration his LATHES a 9" .
 

BGHansen

H-M Supporter - Premium Member
H-M Supporter-Premium Member
Joined
Nov 23, 2014
Messages
726
Likes
1,617
#10
Here's a crazy idea. How about turning a short bushing that will fit over the shaft and have 4 adjusting screws like a spider to center it up. The bushing is closed on the chuck end and at a diameter that'll fit in your chuck. I'm thinking something like a standard die holder for the tail stock pictured below. Of course, the disadvantage is you can't get to the area in the bushing. Plus it'll eat up some distance between your head stock and tail stock.

Bruce

upload_2017-9-11_13-13-30.png
 

benmychree

John York
H-M Supporter-Premium Member
Joined
Jun 7, 2013
Messages
998
Likes
565
#11
To support the outer end of the tube, make a "spider", a disc of steel with 3 or 4 radial holes on it's periphery, tapped for square head setscrews, perhaps 3/8 NC, the disc will have a center hole facing the tailstock in its center, a pipe coupling of a size that its pipe size will fit through your spindle will be welded in the center of the backside and a piece of pipe screwed in; a cross hole is drilled through the pipe to locate the spider axially with regard to its necessary location inside the end of the workpiece. P pin is made to fit the crosshole, and it will bear against the end of the spindle, so the spider will not slide back into the tube against the pressure of the tailstock center. The setscrews are used to center the outer end of the workpiece similar to chuck jaws and allow safe facing and turning cuts or shallow boring cuts in the very end of the workpiece. If a shallow counterbore is made in the end of the tube in this manner, a steel disc can be inserted into the counterbore (fit tightly) so that when the part is turned around for boring from the other end, the chucking pressure will not distort the tube, and also it plugs that back end so that coolant is not thrown all over the place by the chuck jaws,
This method is especially good for making thin bushings from stock having enough length to allow the wastage of the counterbored part to machine off after the part is finished.
So far as the 7" length of the part is concerned, it will be necessary to cobble up some sort of steady rest. I have made them from steel plate machine burnt and machined up like a normal looking item, I have also made wooden patterns and had the cast in iron, which is the proper way to go about it. For smaller lathes it may not be necessary to make the rest hinged as most are; I just made one for my 9" Monarch lathe from the WW-1 era, A friend had an original, so I just copied it; it was made solid, no hinge, but with the front section open where the normal fastening point would be. For a small lathe it is not so important to have the hinge feature, and it is lots simpler to make.
 

benmychree

John York
H-M Supporter-Premium Member
Joined
Jun 7, 2013
Messages
998
Likes
565
#12
Here's a crazy idea. How about turning a short bushing that will fit over the shaft and have 4 adjusting screws like a spider to center it up. The bushing is closed on the chuck end and at a diameter that'll fit in your chuck. I'm thinking something like a standard die holder for the tail stock pictured below. Of course, the disadvantage is you can't get to the area in the bushing. Plus it'll eat up some distance between your head stock and tail stock.

Bruce

View attachment 241446
Technically what you describe is not a spider, but a "cat head" or maybe derived from "cap head". Using a spider inside makes the job much easier as several operations may be done in one setting of the workpiece. Also called a spider is a sleeve that will fit over the workpiece, having two rows of setscrews for centering with enough space between them to allow the steady rest jaws to run between them.
I once machined some very long crane drum shafts that were rough forgings, they were so limber that chatter was a large problem, so a spider of that sort was located about in the middle of the shaft and adjusted to run true and steady rested; no more chatter problem. A cat head can be used on a similar job to center the end of the shaft accurately enough so that a steady rest spot can be turned behind it, steady rested, the cat head removed and the shaft end properly faced and centered. If the workpiece were a piece of cole finished shafting, no problem, but we were working with roughly hammered forgings that could not be steady rested.
 

12bolts

Global Moderator
Staff member
Active Member
Joined
Apr 23, 2011
Messages
1,929
Likes
368
#13
Well, my chuck with the outside jaws (the ones that grab by pushing out)
Bill, just as a matter of clarity and future reference, the description of chuck jaws describes the location of the jaws on the work. Outside jaws are outside of the work and operate by pushing inwards.

Cheers Phil
 

Bill Kahn

Active Member
Active Member
Joined
Mar 19, 2017
Messages
38
Likes
10
#14
Bill, just as a matter of clarity and future reference, the description of chuck jaws describes the location of the jaws on the work. Outside jaws are outside of the work and operate by pushing inwards.

Cheers Phil
Thank you. So much to learn. How to hold on tight to a 25 lb chunk of steel and also the name what I am suppose to use to do so. All lessons gratefully received.
 
6
5 7