Solid Tool Post Riser for my 13"x40" lathe

ChrisAttebery

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I bought an import 13"x40" gear head lathe a couple years ago (https://www.hobby-machinist.com/threads/new-to-me-yangzhou-ty-co632-13x40-gear-head-lathe.65871/). As others have noted the compound on these lathes isn't very rigid so I decided to try making a solid tool post riser. I made some measurements and came up with a design in Fusion 360. I designed it so that there aren't any ledges for chips to get caught between the tool post and holders.

Front:
Solid Tool Post Riser 1.jpg

Back:
Solid Tool Post Riser 2.png

Top Down:
Solid Tool Post Riser 3.png

I still need to add an L shaped plate to lock the tool post in at 90 degrees.

I wanted to use cast iron or steel for the riser but I couldn't find new stock anywhere nearby and buying a block and having it shipped was going to be about $150. I decided to try looking through the scrap at the local metal dealer. The only block I could find that fit my minimum dimensions was a block of scrap A36 steel 7.25" wide, 2.75" tall and 6.3" long. None of the sides were flat. It was only $15 though, so I don't mind doing a couple hours of machining.

I don't own a metal cutting band saw and the block was too big to fit on my Evolution Rage 2 chop saw. So I loaded it up in my CNC converted G0704 and milled away 48 cubic inches of steel (~13.5 lbs.). I used a 3/8" 4 flute carbide end mill at .630" DOC, .025" WOC, 4000 rpm and 40 IPM. That's roughly .5 cubic inches per minute. Two hours later I had a huge pile of chips (at least by my standards).

IMG-7788.jpg

Once I got the block down to a reasonable size I thought I'd try facing the ends on my lathe. This is the largest piece I've turned with it. A 25lb block spinning at 300rpm was a bit scary at first, but it was reasonably balanced and the ends cleaned up nicely.
IMG-7789.jpg

At this point I have a block that's the correct width and the sides are parallel. The top and bottom aren't perfectly flat and the end faces are neither parallel to each other nor perpendicular to the top and bottom. My plan is to face the bottom, the top, and then reface the ends. That should give me a nice square block. Then I can start milling the final shape out.
 
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Good job ... but I think it's high time you treated yourself to a bandsaw!
 
Last night I got the top and bottom milled flat and pretty close to parallel to each other. Then I moved the piece over to the lathe and faced the ends so that they are square to the top, bottom, and sides. There are a couple places where the surface isn't smooth, but they will be milled away so I'm not worried about them.

At lunch today I used a 1/8" roundover mill to round off the vertical edges of the block. At this point I think I'm ready to start milling the riser out of the block.

IMG_7801.jpg

IMG_7802.jpg
 
ericc, I don't know if I'd go that far, but it's the biggest project I've taken on. Before this the largest piece of steel I machined could fit into the palm of your hand.
 
Hi Chris. I would love to hear about your experiences and evaluation of this block after you install it. I did a similar project for my South Bend 9, and it did not help as much as I thought. Either the compound is pretty solid or something else is loose. It did seem to help somewhat.
 
Sometimes I can see the tool post flexing on my machine. I've examined the compound and I can see why it's the most likely culprit. The way its connected to the cross slide is pretty weak. There are two 8mm bolts holding it down and the contact surface is pretty small. The tool post is also cantilevered off the end. There's only one way to find out if it makes a difference.
 
Chris,

Interesting design and concept, when I bought my QCTP, I was told the weak joint is at the compound/carriage, but we do the best we can. It would never work for me, I use the compound on a regular basis and am constantly pivoting the QCTP on my 14 x 40 Jet. Still I’m very interested to see the results.
 
Sometimes I can see the tool post flexing on my machine. I've examined the compound and I can see why it's the most likely culprit. The way its connected to the cross slide is pretty weak. There are two 8mm bolts holding it down and the contact surface is pretty small. The tool post is also cantilevered off the end. There's only one way to find out if it makes a difference.
It makes a difference. I replaced the compound with a tool block on both my lathes. They got more rigid and finishes were improved. It was a big help with parting.DSC_0825.JPGLOGAN LATHE 2.JPG
 
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