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Has anyone used a high shear angle face mill on straight grain and figured wood? Smooth as silk? Prone to tearout?

I was able to answer my own question last week. I bought one of these

http://www.rotarytech.com/category_listing.php?id=2

Tried it on flame maple. It didnt tear out the grain but the surface finish wasn't as nice as say a jointer. I think it would be a great finish for gluing though.

You can get a great finish with a face mill, but the inserts really matter. I don't know if the round inserts would be as effective on wood, they usually don't make really high rake aluminum inserts in that profile which makes me think there's some reason for it.

Try putting in only one insert. It can work really well on things where you don't need extra edges to get more feed rate. It works great on aluminum to prevent rubbing / galling at high RPM, and it stops burning the surface on wood.

Getting a really good surface on wood needs either really sharp cutters, like razor sharp, or extremely high edge speeds. Larger face mills can get crazy edge speeds, so they can get by with duller inserts. You can run a 5 or 6" on the Fadal.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

I'll vouch for that. I have a 5" face mill that holds 6 inserts. Doesn't seem to make much of a difference how many bits I use so I use two. If I were to use all six bits I could have high feed rates...but that doesn't much matter to me as long as I can get over 120 ipm or so. My smaller machine gives me overspeed alarms at 200 ipm. The big one can go much faster.

The bits are a high rake angle...for metal. They don't appear razor sharp though I do get a pretty good result with softer woods. The most effective trick for softer woods for me was to use a small stepover that keeps the attack angle of the cut relatively parallel to the grain. When the cut goes from 45 degrees to ninety degrees relative to the grain the rip out increases dramatically. This means a stepover that is 1/4 the diameter of the tool. It would take a while to surface a body with a small diameter tool so here's where the 5" face mill comes in handy. It weighs 13 lbs. I get a little uncomfortable using outside of the Haas limit of 12 lbs.

But when it comes to surfacing soft woods with a complex surface using a ball mill....I think rpm is the only real parameter that can affect finish. I wish I had a high rake option for the ball mill...which I haven't really seen outside of a insert type cutter. I haven't purchased one of those yet but I'm thinking about it if I can find the right configuration.

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

Not trying to hijack this thread, but I have needed to ask this question for a long time, and this thread reminded me of it, as well as giving me opportunity.

In addition of machining multiple kinds of wood, I also machine polysterene, both extruded and eps. I have need for a large diameter bit but can only handle a 1/2" shank. I need a long bit, maybe 8" long, with .500" shank but a cutting diam of maybe 1". The kicker is I need to be able to spin it at at least 7-12K rpm but need it balanced.

Would it be possible to have a blank made of titainum and use steel inserts, or carbide for that matter. This would be a ball nose. I need the weight reduced to to lack of horse power in the spindle! 3.5hp is max from a converter controlled water cooled spindle.

Mike

A cutter in that aspect ratio on a small machine is a recipe for disaster. It's a lot of mass, the length will multiply the tiniest bit of runout in the spindle even if flawlessly balanced, and I'd assume from the shank limit that you'd be holding it in a collet.

You can get very long 1/2" cutters, up to 6" easily and maybe 8" if you really look around, which will greatly reduce the spindle destruction chance. Alternatively, if you're set on doing this, you can get what's called an ER collet extension or ER straight shank collet chuck which is a shank with an ER collet chuck on the end of it. Then you can stick a core box bit in the end of it, which'll be a large ball-end with a smaller shank.

You can Google around for the collet chucks, and the woodworking tooling places like Amana will have core box bits (even with inserts!). I think all the EPS places are just blowing it into molds...is it possible that making the molds is a better way to go? I don't know the process for 'filling' the molds, mind you, but I assume it's similar to the foam we inject into walls and such.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

That sounds scary.

However, have you seen these?

http://3dcutting.com/products/frogtools

http://www.toolstoday.com/p-5714-insert-spoilboard-surfacing-rabbeting-router-bit-with-scorer-2-2-design.aspx?variantids=8905,0
Too late for Sheldon's initial question but for what it's worth.

Bob the spindle is a 3.5 hp atc unit that was assembled in China but the parts for the spindle was machined in Japan.....so says my seller, and he is a guy that has proven himself to be very reliable. It uses ER20 tool holders, and yes, I think each tool holder has a collet, though it is called a "precision" collett. I have to buy those seperately of course and have not really started the looking process, but if it is like everything else, price will be all over the place as well as the quality of parts I'm sure.

No...my intent is not to have a custom bit made if I can find anything that will work, and maybe Sheldon's link will provide me a source.

Thanks to you guys for your input.

Mike

Funny how after getting my Super PID II for my router that the end mills I buy now work so well on wood vs the choice of router bits I was using when starting out in CNC routing (Also the noise factor ). By having the ability to finely adjust my spindle speed it makes it much easier to make a choice in the end mill I purchase for my specific needs.


MK

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Bob the molding would be great except everything I am doing is one off....Lord willing, I will be delivering the last parts for this late this week, early next!

Mike

If you're looking for a face mill, I'd check these guys out: http://www.glacern.com/fm90

I have some of their insert cutters and their stuff is prime.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

How big is that thing in the real world, Mike? That's a pretty substantial project!

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

Bob it is a full size car. Yes it is a very large project and therefore my need for a larger diam cutter with depth so I don't have to make so many passes.. We have discovered, it is actually quicker to take a little larger step over, then hand smooth than it is to step it say .04". What I want to do is step it about every .125" and still have a relative smooth surface with much less hand work. This car will come with two different front or rear caps available and is quite a project.

As soon as I get this done, I can, if I want, start on three more projects......but before I do, I really want that bit!

Mike

ps you want me to post my picture in mine when I get it built? I get car #2

Of course!

A photo of the process would be nice too.

Wow, great prices. The prices suggest Chinese manufacture, but you say the stuff is top quality? I could use one of their vises and a drill chuck.

I think the cutters they do entirely in house, but I might be wrong on that one. They buy vises from a Chinese manufacturer and then precision grind them at their facility. It's a good business model.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

I agree, searching around various forums I've heard nothing but praise for their quality, service, and support. I'm convinced enough to order a couple of the 6" premium vises, the 5" high shear face mill and arbor plus a bunch of inserts and tool holders.

I believe they source the castings from Taiwan and machine them in house at their facility in LA. Excellent website too.

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