CNC router: suitable for FRC?

[techhelpbb]

We have a Haas TM-1P with 10 position tool changer and a Haas TL-1 on the way (it might be there already or not with the snow). On the manual side we have an old Bridgeport knee mill.

We've not done too much with the Haas yet at FRC but from experience it'll handle the jobs just fine. Just realize it's expensive, depending on the software that could be expensive, and then there's the tools. This is not really a hobby machine it's a professional tool.

[CENTURION]

Personally I know I'd love to get my hands on a CNC router for our FRC and FTC teams. Being able to easily do sheet metal parts would be really nice.

Although, I want to throw this idea out there; build your own.

I've been following this fella on youtube for a couple years, and he's build a fantastic, high-accuracy (for a router), powerful, machine for about $2500, and with the kind of expertise that you have with FIRST teams, it could totally be pulled off. And he even has some good how-to videos if there are things you get stuck on.

And http://www.cnczone.com/ is a great resource.

You still might find that buying one is better for you, I just wanted to throw it out there.

[Mulcahy]

We have a shopbot. It gets used as much as any machine in our shop - including the drill press and cnc mill. You can cut aluminium with a single flute cutter. The end product is not as finished as it is on the mill, but the ability to rapid prototype is priceless. We also make a lot of mock-ups using MDF and Lexan to check the fit of parts before they are sent out for final machining by our awesome sponsors. I would highly recommend getting one.

[Leav]

Hey everyone!

thanks for the replies!

just to clarify: when I said "aluminum profiles" I actually menu "aluminum tubing, mainly rectangular".

from your answers I gather that it's possible but maybe not the best idea.

does no one make CNC routers intended to cut aluminum?

[techhelpbb]

Originally Posted by Leav

Hey everyone!

thanks for the replies!

just to clarify: when I said "aluminum profiles" I actually menu "aluminum tubing, mainly rectangular".

from your answers I gather that it's possible but maybe not the best idea.

does no one make CNC routers intended to cut aluminum?

If you take a look at my post you'll see that the Haas TM-1P can machine just about anything an average Bridgeport can which includes aluminum. It's more than fast, powerful and rigid enough, it's got coolant and with the proper tools it'll do a great professional job.

Gantry routers will do aluminum but there are limits in speed, power and rigidity. I've cut plenty of aluminum on gantry routers just know: your machine, keep the number of flutes down as low as possible, use smaller diameter end mills, and mind the suitable feed rates (you'll mind the feed rates anyway on most CNC machines). If you must use a general purpose shop router as the spindle consider getting a SuperPID for it.

Will these cheaper machines be a 100% replacement for something like the Haas TM-1P: absolutely not. Will they do some work: sure just don't get too crazy. Keep in mind the forces involved and respect them.

[Leav]

Originally Posted by techhelpbb

If you take a look at my post you'll see that the Haas TM-1P can machine just about anything an average Bridgeport can which includes aluminum. It's more than fast, powerful and rigid enough, it's got coolant and with the proper tools it'll do a great professional job.

Sorry I didn't get a chance to click the link when I wrote my post, I was on my phone.
Now that I've clicked, I must say I was taken aback by the price!
We were looking to get something for under $5000.

Originally Posted by techhelpbb

Gantry routers will do aluminum but there are limits in speed, power and rigidity. I've cut plenty of aluminum on gantry routers just know: your machine, keep the number of flutes down as low as possible, use smaller diameter end mills, and mind the suitable feed rates (you'll mind the feed rates anyway on most CNC machines). If you must use a general purpose shop router as the spindle consider getting a SuperPID for it.

Will these cheaper machines be a 100% replacement for something like the Haas TM-1P: absolutely not. Will they do some work: sure just don't get too crazy. Keep in mind the forces involved and respect them.

I think that's an important thing to take from this: If we're willing to keep feed rates down, It would probably be ok to use a gantry router.

This is good news as far as I'm concerned, since the gantry router form factor is better suited to our shop (the ceiling is pretty low, about 3m/9feet at most).

Thanks everyone! i'll be back when we compile a list of optional machines and i'll ask for your opinion again.

[RandomStyuff]

Don't know if this question fits here or in another thread but it felt very related. A few weeks ago I saw the Shapeoko 2 CNC router (http://www.shapeoko.com/) which felt to me really inexpensive relative to the option of a CNC mill. I assume nobody would have experience with the new version but does anyone know based on the old version if it would be something that fits for FRC uses?

Would it be possible to use such equipment for things like making gearbox plates or a drive system frame (in terms of accuracy). I understand that routers take longer than mills, but I expect being able to do slow is better than not being able to do at all .

I've found it including some more details and price here: https://www.inventables.com/technolo...kit-shapeoko-2

[DonRotolo]

Originally Posted by Leav

I think that's an important thing to take from this: If we're willing to keep feed rates down, It would probably be ok to use a gantry router..

Emphasis mine. No, you need to calculate the correct feed rate based on the tool (router bit) manufacturer's specification, and take a smaller depth cut. Taking too small of a 'bite' (from a low feed rate) is just as bad as taking too big of a bite (from a high feed rate). Look up the term "chip load".

But yes, if you are willing to keep the pass depth down to maybe 0.125 or less, cutting aluminum (including profile) is not a problem.

Except, longer tools will be needed to cut the entire thickness, and these are less rigid than short tools. For example, I use a 3/16" diameter cutter with a cutting length of only 3/8". I cannot cut anything deeper than 3/8". But this tool is very rigid and doesn't deflect much at the proper feed speed (60 IPM, 12000 RPM, 3/32" pass depth (=1/2D)). A tool with a cutting length of, say, 1.25" will be less rigid, but it will cut 1" box stock without trouble - but maybe only at 40 IPM, 8000 RPM, and perhaps only 0.06" depth. (The tool bit can cut at 1D pass depth, but the machine cannot supply that kind of force)

[DavisDad]

Originally Posted by DonRotolo

Emphasis mine. No, you need to calculate the correct feed rate based on the tool (router bit) manufacturer's specification, and take a smaller depth cut. Taking too small of a 'bite' (from a low feed rate) is just as bad as taking too big of a bite (from a high feed rate). Look up the term "chip load".

But yes, if you are willing to keep the pass depth down to maybe 0.125 or less, cutting aluminum (including profile) is not a problem.

Except, longer tools will be needed to cut the entire thickness, and these are less rigid than short tools. For example, I use a 3/16" diameter cutter with a cutting length of only 3/8". I cannot cut anything deeper than 3/8". But this tool is very rigid and doesn't deflect much at the proper feed speed (60 IPM, 12000 RPM, 3/32" pass depth (=1/2D)). A tool with a cutting length of, say, 1.25" will be less rigid, but it will cut 1" box stock without trouble - but maybe only at 40 IPM, 8000 RPM, and perhaps only 0.06" depth. (The tool bit can cut at 1D pass depth, but the machine cannot supply that kind of force)

Thanks for the detailed info DonRotolo. Really helpful! Am working on lightening cutouts. What about a miniature chop saw between 1/2 diam drill holes?

[DonRotolo]

Originally Posted by DavisDad

Am working on lightening cutouts. What about a miniature chop saw between 1/2 diam drill holes?

I don't understand the question.

[DavisDad]

Originally Posted by DonRotolo

I don't understand the question.

I'm interested in a non CNC method for making these lightening cut-outs (1/4" Al):
'



By drilling 1/2" holes and cutting between with something like this:



Your thoughts appreciated.

[DonRotolo]

Ah. OK.

Um, no. I don't think you can control a chop saw carefully enough to do it.

Traditional method would be to drill holes, and then use a jigsaw or scroll saw to cut out the openings.

Less common method would be to use a wood router, hand-held, with a 1/4" or larger aluminum-cutting bit, using a plywood or MDF template, and a bearing or collar, to cut out the 'triangles' after drilling access holes. Note that this is more dangerous than average, gotta be super careful and slow (about 1" per second). And hearing/eye/skin protection is mandatory. (We did this with 3/16" aluminum some years ago, nobody died...)

Of course, you can also do it with a coping saw. Assign it to a freshman.

[Akash Rastogi]

Originally Posted by DonRotolo

Traditional method would be to drill holes, and then use a jigsaw or scroll saw to cut out the openings.

Print your CAD drawing scaled 1:1, tape it to wood, cut out wood part using bandsaw + scroll saw, proceed to use wood template on metal part + scroll saw. You can just tape the paper to your metal, but I like having the wooden part as well.

[DavisDad]

Originally Posted by DonRotolo

Ah. OK.

Um, no. I don't think you can control a chop saw carefully enough to do it...

What if the piece were clamped fast in a jig that controlled the depth of the plunge cut; there would be a stop to control cut length/depth?