Atlas 7B Shaper block replacement

[jhmiii]

I purchased an Atlas 7B shaper last year. It is in excellent shape(!) and was working fine, though I did not use it much. There was a slight knocking from inside, but I was getting cuts with a decent finish. The knocking got progressively worse. This coincided with a pronounced vibration and the finish deteriorated. I opened the shaper this morning. The ram lever seemed tight. I took the plate off of the ram lever and pulled out the block (part S7-19). The block was still a nice fit on the the bronze (?) pin and was well lubricated. The block had a ~1/16" ridge on along one of the long sides. As I looked closer there were ridges on all four long (sliding sides) corners. I think I found the problem! I have attached a picture of the block. Hopefully this is the only problem.

I plan to make a new block and this brings up the reason for this post. What size should this block be? I measured the width of the ram lever slot at 1.504 using a hole gauge. How much clearance is appropriate?

My second question is material. I have a 3/4" X 2" block of hot rolled steel. Will this be okay or should I purchase something else?

Thanks for any help you can provide.

John

 

[francist]

I made a similar block for my Peerless 8” shaper a couple of years ago but used acetal. It has good lubricity to start with and I felt it would be least likely to cause further wear on the sliding surfaces of the arm (the block I was replacing was made of bronze). I cut in oil passages and although acetal can be used dry I keep it oiled as if it were any metal one.

As for size, I made the block as close to the size of the opening as I could without binding or snugging up during the course of a full stroke. In other words, I didn’t deliberately add a measurable amount of clearance. An adjustable parallel was really helpful here to test for just the right fit before going to the machining. So far it seems to be holding up fine.

-frank

 

[ErichKeane]

See the discussion here: https://www.hobby-machinist.com/threads/atlas-7b-disassembly-and-teardown-pic-heavy.84697/ If it is the same part, It hink they have even the original plans. I think that wants to be some sort of Bronze/oillite.

 

[jhmiii]

Thanks Frank and ErichKeane. I appreciate the help.