What type of end mill do I need?

[jderou]

Does anyone have experience machining aluminum with a porter cable laminate trimmer (mounted on gantry cnc)? What type of end mill do I need? Will the router hold up? Feed rate, etc. I'd post a pic of the cnc table but I'm having problems uploading it, I get an error every time I try.

Thanks,

Joe

[M_D]

There are doubtless many options that would get you by, but if you provide some more information it could help in making sound recommendations.

How thick is the aluminum, and what alloys?

What are minimum and maximum depths of cuts?

What are the most important qualities, tool life, fastest cutting speed, the smoothest finish possible, or tool price? I know is nice to have it all, but you usually need to compromise at least one factor.

Will flood coolant, a mister, or air blast be used, or does it have to run dry?

What rpm is the motor, and is it adjustable? Assuming the rpm is high, carbide is likely the best, if not only, logical choice.

What size(s) would you like to use, and what sizes can your machine accept?

I don't know how they (your router) will hold up, but I can tell you it could be very much dependant on how heavy you load it in the cut, and whether you can run without chatter (or at least heavy chatter).

Your optimum feed rate (or chip load) will depend on many factors, such as work piece rigidity, machine rigidity, rpm, horsepower, depth of cut, type of cut (slotting versus light profiling, or shallow engraving, for example) if and how much coolant is used, and etc. Also, the specific tool will make a very real difference.

Sorry I didn't spit out absolute numbers and specific recommendations, but it would be hard to do that without more information to go on.

[Rob D]

Sorry I didn't spit out absolute numbers and specific recommendations, but it would be hard to do that without more information to go on.

Thats as much as any tool manufacturer would give knowing exactly what a machine can do.

Get your feet wet. Start at conservative speeds and feeds then crank er up. .

Rob

[jderou]

Thanks for the info, I am planning on running a flood coolant when I try it (no air compressor yet). I think the machine should be rigid enough, I just don't know if the router will have enough torque for a decent feed rate.
Does anyone have advice on fixturing? When cutting something out of a sheet, how do you keep the piece you are cutting out from moving on the final cut?
I'm pretty much new to machining metal, I've been working with wood for a while but that's easy.

[Ken_Shea]

Joe, unfortunately it would be anyone's guess what you may need (guessing can be costly and dangerous) with out more information on things such as M_D mentioned.

What are you calling sheet?

One method is contact cement on a sacrificial board under the sheet then heat and remove, use clamps, screws it just needs to be secure.

Since the trimmer probably has a .250 collet use a .250 cutter, it is hard to go wrong with carbide and the cost of these is very competitive now for standard carbide cutters, advance geometry or special coating can jack the price up a bunch but I doubt you will need that at this time. I buy most of my cutters from this guy.
http://www.american-carbide.com/default.aspx

[jderou]

Didn't think about the contact cement, that sounds good. Are their any brands that work the best? Should I just use mdf or particle board for the sacrificial sheet? Have you ever tried hot glue? I was thinking in the area of 1/8 to 1/4 thick sheets.
Sorry so many questions!
Thanks again

Joe

[M_D]

jderou, I was envisioning that you might have a 1/4" collet also. Tell us more about the machine and material using the questions I posed above for a guide if you want more specific recomendations.

I assume your rpm will be high, probably "too" high in some regards, perhaps it is 15,000-20,000 rpm? . A cutter actually has a chip load range where it works best, assuming it is the right cutter for the job to begin with. If the chip load is too light, it tends to chatter which makes all kind of unpleasant sounds, chips carbide tool edges, and leaves a poor finish. The theoretical feed rate for that much rpm will tax even some modern CNC machining centers ability to travel that fast in certain profiles. If you have a 4 flute cutter, and figured a .0015" chip load per tooth, that is 90 inches per minute feed rate, which is moving right along, which may be beyond your machines comfort zone. So, you might look at 2 flute endmills if your rpm is indeed in that rpm range, as they will tend to run smoother, and take less power.

Also, you may have seen the high helix end mills advertised and used primarily for aluminum. We use them alot on machining centers, but you probably want to stay with a standard helix. Reason being is the high helix rate tries to pull the end mill out of the collet and at the same time pulls up on the work piece. Not the hot setup unless the collet chuck has adequate holding power and the work piece is rigid and fixtured securely.

The flood coolant is best, at least on aluminum, and if you can deal with containing the mess it will be best from the cutting condition perspective.

Also, you will probably be best off to avoid longer end mills when ever possible, and if you have a buying choice you may be wise to choose a "stub" length. Insert it into the collet as far as conditions allow, if possible up to the flutes. This will improve tool rigidity and decrease the tendancy for chatter.

[kong]

There is a single flute cutter available, specifically for routing aluminium. Made by Belin-Yvon, I have no idea where you would get them in the USA, but they were mentioned in a previous post some months back if you want to search for it

[jderou]

Yes it is a 1/4" collet, and I think it is actually 20 - 30k rpm. I'm trying to upload a pic of my machine but it keeps giving me an error, anyone know why? file size is 100k

[M_D]

I think there is a size limit on the file size, and yours may be to large.

That's a lot of rpm, something like a single flute might work good, especially in aluminum under 1/4" thickness.

[jderou]

Test

[High Seas]

SOLID! And Very Nice. I like how you handled the PC Trim Router mount, Is it bolted thru the base to an L bracket - Is that what I see there? Clever approach. Cheers - Jim