So I got my mini lathe and will say for a guy that has no idea what he is doing I am impressed. So after a few hours of tinkering with the 4 jaw I feel comfortable indicating work in. I made a spider for the machine from a piece of thick wall 5 inch od with 8 , 1/2-13 cap screws spaced around equaly in two spots around 2.250 between centers of holes. I have a gauge pin set that I am using to indicate with and am having issues. I am trying to set back the shoulder of a smith and Wesson 1917 barrel I cannot get it to run true. The indicator closet to the tailstock I can adjust the screws until its zero all the way around. The go back to head stock and its out there. I adjust until its zero go back to original point its out again too. How do you do this?
Barrel work in mini lathe spider
- Thread starter KY DAN
- Start date
- Status
A picture or your setup might help. I am having a hard time understanding your issue. And it would be cool to see your lathe!
hobby-machinist.com forums will likely have better advice about running your lathe... and the members are much nicer than many other machinist forums.
hobby-machinist.com forums will likely have better advice about running your lathe... and the members are much nicer than many other machinist forums.
Kp321
Member
That job could be handled with the barrel between centers, using a face plate and drive dog in place of the four jaw. If your bed is long enough, the most accurate set up on a lathe is between centers.
How long are your range rods, and do you really need to indicate both ends. Some barrels are bananas. Less is more. Personally i'd dial in chamber end and go.
If you can get it between centres, do.
With long rods you can run 2 DTIs a couple of inches apart, which will show you pretty quickly which way you need to go.
If you can get it between centres, do.
With long rods you can run 2 DTIs a couple of inches apart, which will show you pretty quickly which way you need to go.
MachIVshooter
Member
The type of tool your talking about is called a cat's head; a spider would be a 4-screw piece on the back end of your spindle or in a steady rest.
Getting work dialed in on a cat's head is tedious. I can dial a bore in less than 5 minutes on my Hardinge through the spindle with a spider on the back end, but it's usually at least 10 minutes, often more, on my bigger machine with the cat's head. Remember, when you make an adjustment at either end, you're going to move both the bore axis and center. The further from the front set of screws you are indicating, the greater the change will be.
Gauge pins really aren't long enough to do what you're trying to do, either. Turn a 4"+ piece of stock to fit the bore snugly, insert it into the bore about 1"-1.5" and then space your indicators as far apart as possible. I like brass for this, as it will not scratch a bore, but I do have to check the rods every time to make sure they're true, especially the smaller caliber ones.
That said, as mentioned above, there's nothing wrong with between centers for what you're doing. Axial alignment is important for chambering barrels & threading muzzles, but for what you're trying to accomplish, between centers will be faster & easier with no downside.
- Status
