light cuts in alum.

[gunsmith]

Using WD40 doesn't help. When I am plaining aluminum heads is when I have the problem. For what every reason I can not always get a smooth cut when I am only lightly palaining (.005 or less) but no problem with deeper cuts. I am using HSS cutters sharpend to the 9's. Is there a better cutter, indexable or otherwise for this purpose? I have my cutter set up in a fly cutter configuration in my boring head on my mill.

[billyboy]

hi,
you may get a better result if you use paraffin as a coolant on aluminium, also check the cutting edge on the tool as a build up of alum seems to weld its self right on the cutting edge and this can sometimes cause a trashy finish. other than that im sure someone else on here will be able to give you more guidance.

bill

[C. Tate]

Increase the clearence angle. You may be dragging.

Cutting changes the material condition troughout the shear zone. Aluminum as well as other materials will have compressive resdiual stress built up from cutting. You may need to go deeper to get past that layer.

[This message has been edited by C. Tate (edited 08-17-2005).]

[WJHartson]

If the .005 cut is the first cut you could be running into a lot of oxide and this is affecting your tool as it is hard and abrasive. The deeper cuts get under this layer and the chips carry the oxide layer away without affecting the cut. Look at your chip from the light cuts and compare them to the chips of the deeper cut.

Added, are these virgin cast heads that have never been machined before. If that is the case the surface will have all kinds of impurities in it and the .005 is way to light to get below this layer.

Joe

[This message has been edited by WJHartson (edited 08-17-2005).]

[gunsmith]

This is the problem however. I do not have the option of going deeper. My max cut is .005. In fact that is a large amount and it is driving me nuts. They would prefer I cut even less. I am constructing custom racing engines for snowmobiles. If the work I am doing could be done while the castings were rough and I could cut whatever to my finished depth there would be no problem. They come into the shop finished and I have to complete the custom work. Is there a cutter with a finsh that would be more friendly on alum.. This "paraffin" is it the same as what you use to seal jamb jars? If so how is it applied or do you desolve it in a suitable liquid?

[IOWOLF]

Are you running a "wipe" on the cutter? or how about a rounded cutter.

[Michael Moore]

.005" maximum sounds like you could put them on a surface plate covered with W&D sand paper and just sand them down. Change direction while you do it and finish with some finer paper and they might be plenty flat enough.

cheers,
Michael

[darryl]

'using a fly cutter'- I'm wondering if it's possible for you to set an angle on the cutting edge such that it shears rather than chisels the material away. If you touch the cutting edge down to the workpiece, then look from that point of contact towards the axis of the flycutter, does the leading edge of the cutter parallel that view? What I'm suggesting is that looking along the leading edge of the cutter your view should take a line behind the rotational axis of the flycutter (spindle axis). I hope this is understood, and I don't know if there's a way you can adjust for this short of grinding this shearing angle into the cutting bit. Note this is not relief angles I'm talking about. I'll post a pic of what I'm suggesting if it comes to that.

[C. Tate]

If you have a good mill i.e. bridge or similar not a three-in-one or table top then:

Ditch the single flute HSS boring head rig. Buy a multiple flute indexable face mill. There are some very good aluminum only tools out there. Iscar makes the best I have seen. It is not cheap nor are the inserts but it will do the .005 pass and the finish will be supurb. If you do not want to make that investment then buy a true fly cutter and use brazed carbide tools. The home brew fly cutter and hand ground tools are going to be a battle. Boring heads are for boring and hand grinding good tools is an art.

CT

[C. Tate]

Ditch the homebrew fly cutter for true facemill. Iscar makes supurb mill for alum. If the investment is to great buy a true fly cutter and use brazed tools. Boring heads are for boring and hand grinding tools is an art.

CT