Milling advice wanted - new to milling

[cederholm]

Hello everyone,

I'm new to milling and I'm trying to learn on my Maximat Compact lathe with vertical mill. One of my early projects is to remove .150 off of some Chinese made quick change tool holders for the lathe. I'm using a 1/2" four fluke endmill and I'm removing .050 in each pass. My problem is that I keep chipping of the cutting tips of the endmill. The first dovetail pass goes pretty well (see Fig. 1 and note the arrow indicated the bed travel direction) the second dovetail pass is a little more choppy and by the time I've finished removing the whole .150 my tool is pretty chipped up.

I'm feeding ad a very slow rate (because I'm scared) and I'm using oil.

Any advice would be greatly appreciated.
~ Carl

Fig. 1


Fig. 2


My machine

 

[Jim2]

A couple of comments. It looks like you're climb milling. That's probably not a good idea on a home-shop machine unless on a very light finishing pass. See http://www.cnccookbook.com/CCCNCMillFeedsSpeedsClimbConventional.htm to see difference between climb milling and conventional milling.

That setup looks pretty shaky. It would be a good idea to support the work closer to the spindle by lowering the head, or using a riser block or such. I've never used a 3 n 1 machine, so not sure how much flexibility you've got with that. Then shorten up the distance between your spindle bearings and where you're cutting. A smaller endmill probably wouldn't hurt either.

Toolholders are probably made w/ a hardened steel, so not easy to cut in any case.

Jim

 

[T Bredehoft]

Feed in the opposite direction.

You are climb milling, a big NO-NO for manual machinery. the cutter pulls the work into itself, taking far larger bits of metal than it was designed for. By feeding from the other end, you will be pushing against the rotation of the cutter, and there is no slack in the feedscrew.

One drop of cutting fluid per pass is sufficient, don't flood the work, it just makes a mess.

Climb milling gives a far better finish, and that is desirable, but almost no manual machines can do it well, and for a person in a learning situation, it is not a good choice, as you have found out.

 

[herbet999]

Agreed on the climb milling. Just reverse your spindle motor and see if that helps. Feed in the same direction.

 

[cederholm]

Wow! Thanks for the advice all. Very helpful.

~ Carl

 

[herbet999]

By the way.. love your carriage stop

 

[cederholm]

Thanks Herbert,

Since I have nothing to compare it too, can you explain what you like about it? ...I really have a LOT to learn.

~ Carl

By the way.. love your carriage stop

 

[herbet999]

Sorry, I was being facetious. looks like it does the job and it's bare bones.

 

[cederholm]

LOL!! Yes, that's my next project is to make a proper stop.

~ Carl

Sorry, I was being facetious. looks like it does the job and it's bare bones.

View attachment 93717

 

[cederholm]

Jim, how would I best achieve this? Unless I'm missing something the majority of the space is due to my tool holder. Should I look into collets?

Thanks you,
Carl

That setup looks pretty shaky. It would be a good idea to support the work closer to the spindle by lowering the head, or using a riser block or such. I've never used a 3 n 1 machine, so not sure how much flexibility you've got with that. Then shorten up the distance between your spindle bearings and where you're cutting. A smaller endmill probably wouldn't hurt either.