[longnho]

Hi everybody,
I'm new at milling and try to improve the skill. I get trouble with a project that has 3 inches deep pocket and inner radius (radii) to finish are 0.09 (+/-0.03). Material is steel 4130 heat treated at 200K. Thank a lot for any help.

[Jim Dawson]

Without a bit more detail it is hard to offer advice. If the inner radius is at the bottom corners of the pocket then a bull nose endmill with the proper radius would be the correct tool to finish with. Remove as much material as possible with a roughing endmill first.

[longnho]

Without a bit more detail it is hard to offer advice. If the inner radius is at the bottom corners of the pocket then a bull nose endmill with the proper radius would be the correct tool to finish with. Remove as much material as possible with a roughing endmill first.

Thank you very much for your advice, Jim. the hard thing is the corner radius between walls of the pocket. I had used the small dia. (3/16) ball end mill to finish this corner after roughing around by 1/2 dia. endmill. But seem it was not be successful. the tool was tool long to handle the job, even I tried with many speed & feed situations,

[Jim Dawson]

Can you post a picture of the part? Maybe a screenshot of the CAD drawing. I am having a hard time trying to understand what the pocket looks like. 3 inches deep is too much DOC for a normal 3/16 ball endmill. But there are cutters that might do it. This might be better done on a 5 axis machine or a sinker EDM, does not really sound like a good job to run on a 3 axis machine.

[longnho]

Can you post a picture of the part? Maybe a screenshot of the CAD drawing. I am having a hard time trying to understand what the pocket looks like. 3 inches deep is too much DOC for a normal 3/16 ball endmill. But there are cutters that might do it. This might be better done on a 5 axis machine or a sinker EDM, does not really sound like a good job to run on a 3 axis machine.

EDM is the first thing I though but the customer doesn't like to use EDM So I have to mill that. project 1.pdf

[Jim Dawson]

I'm not sure that the customer is in charge of determining the best way to machine the part. But in any case, it looks like the only difficult radius to machine is at the bottom of the 70° angle, a wire EDM would be best here. I would start by drilling a 3/16 hole through that area then blend the radius with the endmill.

That part is going to require at least 4 (and I'm sure more) setups at different angles just to do the features that I can see on the drawing. Then I can see a number of 3D profiling routines required. For some of the areas a lollipop cutter might be required. Order of operation is going to be interesting. If you don't have a 4 or 5 axis machine, then at the very least you would need to set this up on a vertically mounted rotary table or spacer to be able to reach some of the features.

I hope you bid this one pretty high because it is worth a lot of money. The actual machining time isn't that great, but the setup time and fixturing is substantial.

[longnho]

Thank you very much for your advice. I don't have a 4-axis so set up part on a rotary table is a great idea. I'm thinking about cutting the bottom of the 70 deg angle on a manual horizontal mill with arbor support, but I have no idea what kind of cutter would handle this (teeth, material of cutter..). would you have any suggestions?

[Jim Dawson]

A radiused tooth cutter of proper diameter would work, HSS would be fine. Going to have to be a pretty large diameter cutter, something like 6 or more inches, is your horizontal machine large enough to handle a cutter that size? Something like this, except with a tooth radius. https://www.globalindustrial.com/p/m...tter-6-58-1-14

A bull nose endmill on a vertical machine or even on your horizontal would work also. Maybe something like this https://www.the-carbide-end-mill-sto...-30-altin.html

[longnho]

thank a lot. I will try those tool.