Need Help!- Machine small pins out

[wrechin2]

Hope this is the correct place to post this.... I am working on some 2 stroke pistons and they location pin for the rings. I want to mill them out and relocate them. The problem is they are very small around 1/16" hardened pins and about .600 long. I have broken two 1/8" 4 flute end mill that are TiAIN coated with a spindle rpm of 1,100 with very light pressure. They seem to "grab" and then break. I am having to mill off center to keep from milling the ring groove too much. Can someone steer me in the right direction of what I need to do this correctly? I would appreciate the help. Thanks to all that reply.

[MadMax]

If the pins can't be pulled out, can you grind them with a Dremel tool? If you're working in a bore and can't get a grinding wheel in, you may have to get the pins EDM'd out. How come you can't pull the pins? Not enough to hang on to? Can you weld something to them to haul on?

[wrechin2]

Can not grind pins out as they are in the ring groove and go .500 into the piston itself. I have tried heating the piston at 450 degees for a hour and tried pulling them out.Not alot to get a hold of. I don't have a EDM machine and don't know of anyone who does.

[jmelson]

Originally Posted by wrechin2 Can not grind pins out as they are in the ring groove and go .500 into the piston itself. I have tried heating the piston at 450 degees for a hour and tried pulling them out.Not alot to get a hold of. I don't have a EDM machine and don't know of anyone who does.

Get the thin cutoff discs for a Dremel. You should have no trouble
grinding the pins flush or even just a hair below the valley of the ring
groove with these. You might break a few, so wear eye protection.

Jon

[wrechin2]

The reason for removing them, in during high rpm's, the piston expands and pins are notorious for coming out and causing damage. If left in, they can come out and put pressure on the ring causing accelerated ring/ cylinder damage. I am needing to completly remove then as you go though and put them though the top of the piston and they are fixed in a way they can not come out. The very expensive ($299 each X6) are done this way from the start. I have one that I am trying to copy. I just need to get these pins out. I can send them off and have them done for $50 a piston, but is kind of useless since I can get new pistons for not much more that can handle 9K short burst. I just have a ton of pistons that would be good for 7,300K if I can just top pin the pistons. Thanks for all the help.
James

[Sparky_NY]

Originally Posted by wrechin2 Hope this is the correct place to post this.... I am working on some 2 stroke pistons and they location pin for the rings. I want to mill them out and relocate them. The problem is they are very small around 1/16" hardened pins and about .600 long. I have broken two 1/8" 4 flute end mill that are TiAIN coated with a spindle rpm of 1,100 with very light pressure. They seem to "grab" and then break. I am having to mill off center to keep from milling the ring groove too much. Can someone steer me in the right direction of what I need to do this correctly? I would appreciate the help. Thanks to all that reply.

That rpm is way too slow. Anytime I used a carbide mill to take out a broken tap, slow rpms are a sure killer of the bit. Wind er up and you will have better luck. Also, make sure it is a center cutting type endmill or that will cause breaks for sure.

[wrechin2]

I ran slower rpms as the aluminum was trying to stick to the bit. How do I know if it a center type cutter? I am actually off center as the pin is 1/16 and the ring groove is 2mm. The lower portion of the ring groove in not cut just the pin and the top section. Would a 2 flute be better? I did manage to cut one out and I was more center on it due to it has a 1.5MM ring groove, and had to be more center on it to not damage the lower ring groove. Thanks for all the help.
James