Re: CNC Router/Mill
 

As long as the people using it know what they're doing backlash can be easily accounted for. If you have a DRO it becomes a nonfactor-the reader that slides along the linear scale won't register backlash-only actual table movement.

You're likely mostly going to be cutting aluminum so the 1/2 hp motor wouldn't be that big of a deal. You will have to take very light cuts though.

I can't imagine that a M head would sell for more than $500-750 even in nice condition, but I'm no expert. If you search around online you can probably find some information on it's worth. It's a really, really old machine, which there's probably not much demand for. Lots of nice looking 2J and J head mills sell for $1000-1500 on Ebay, and those are much more machine than a M head.

Re: CNC Router/Mill
 

So if I can't find a J head, would it be better to get something like a RongFu-31 clone (say like HF) or go for the less powerful Bridgeport?

Also, is there an easy way to upgrade the motor on an M head to say something like 1 hp right (since the motors are cheap)? My guess is the round ram head would not like the extra power.

Re: CNC Router/Mill
 

Sorry to interrupt into this conversation, but I was wondering if anyone could point me into the right direction as where to buy bits for a CNC and where to get the Table Clamps. (The bits are for 7075 grade aluminum and the clamps are for sheets and tubes of aluminum). Thank you CD in advance.

Re: CNC Router/Mill
 

If you're going to go for an imported machine, I've read very good things about this mill on cnczone.com

We have this Rong Fu benchtop mill in our trailer that serves as a mobile machine shop at many west coast regionals. We had this JET mill in our lab, but gave it away to 968 since we had no room for it, and came into possession of a second Bridgeport clone. I would never ever buy one of those round column mills of any type. The fit and finish is terrible, and it just feels cheap and junky.

I'm a big fan of the Rong Fu I linked, as far as benchtop mills go. I have used it many times, and it's actually not bad at all for it's size. For FRC purposes I'd say it's very adequate, if you're on a tight budget. Definitely orders of magnitude better than the round column mill-drills. The only thing that annoys me is the Z downfeed handle is some random number/revolution. It's like 0.090" or 0.110" per revolution or something.

Re: CNC Router/Mill
 

KBC Tools Enco MSC/J&L and tons of other companies sell everything you're looking for. I'm partial to KBC.

Just get some simple 2 or 3 flute end mills. either uncoated or TiCN coating for Al. If it's general purpose stuff ignore carbide, as HSS will work fine.

Anything from the box at the top of this page would work fine.

Your question about clamps is very vague. What exactly are you trying to do? There are a vast number of workholding devices out there for a vast number of applications.

Re: CNC Router/Mill
 

Cory, we are looking for clamps that secure either aluminum sheets or 2x2 tubing on a bed of a CNC. This is what we have.

Re: CNC Router/Mill
 

Do you have vise(s)? If not you need some. At least 2, so you can hold a long length of tubing (for making robot side rails, etc).

To hold a plate to the table, search for step clamps on any of the sites I listed above. if the plates are short enough you can hold them on the top of your vise by moving the jaw plates to the outside of the jaw body.

Re: CNC Router/Mill
 

Maybe its been posted before (forgive me) or you already know but theres a pretty good and large website devoted to CnC's and machinist .
They at www.cnczone.com there a lot of info on building your own and buying , using. Might be worth signing up to them.

-p :cool:

Re: CNC Router/Mill
 

And I happen to be a member. :]

On tool bits, also be sure to look around your area. You might be surprised to find out who's selling end mills, etc. in your area if you just need one or two, and would take the convenience over a little lower cost.

Clamp wise, you really should check out . They've been around since like the '50s, hence the awesome space-race logo, and they REALLY know their stuff. Their clamps range from economical manual cam-over clamps to hydraulic auto clamps for high production fixturing.

CNC wise, if you're looking for a project and OK with upgrading some of the mechanical components of the mill (i.e. building a retrofit pre-loaded power nut assembly to get rid of your backlash, for both the X and Y axes) and doing a large amount of wiring, setup, etc. then an old mill retrofit is for you. And for those who say you really have to watch it with a 0.5hp mill... not terribly so. The nice thing about the 0.5hp motor is that it'll make it only slightly more difficult to melt tools into the workpiece since you don't have quite as much power to play with.

However, if you use sharp, carbide tooling you might be surprised at how fast you can cut. Carbide provides a very efficient cut in aluminum... you should be able to do about 0.05" passes with a half inch cutter at about 3000RPM, maybe 20ipm without an issue on your spindle motor.

Of course, spindle motors are NOT that expensive to upgrade (1HP $108, 2HP $137, 5HP $216, 300HP $6967 made you look!), but remember to watch how much heating you're putting in the gearbox with added power... I don't think I'd go much over 1HP, maybe 2HP. But, before you go off and buy big motors, please get out your machining slide table (free from TRW carbide, Niagara Tool, others) or machinery's handbook and figure out how much power you actually need to do the cuts you want to do. You might be surprised.

Of course, you could always build a CNC... it's fun and takes for ever but cool when you're done (we have a homebrew 6x10 foot CNC at work)... but that's another story I'll only tell if asked. ;)

-q

Re: CNC Router/Mill
 

Carr Lane is quality stuff, but it's also quite expensive. You can get the same stuff (lower quality of course, but still plenty good for almost all uses) for much cheaper from the industrial supply giants.

Re: CNC Router/Mill
 

Awesomely, we found a Bridgeport J head with DRO and powerfeed for 2k, sound like a good deal?

Re: CNC Router/Mill
 

The Series I with J head is a good mill, provided it meets the above qualifications that were posted earlier in the thread.

Re: CNC Router/Mill
 

Its in ok shape.

The table has a few surface holes and scratches, and the backlash is up there, but the DRO and powerfeed is really the plus to me.

Re: CNC Router/Mill
 

Hey CD,

We needed some help on our CNC Router Table.

1. I downloaded a couple of calculators and it says when you switch from cobalt endmills to carbide the spindle rate goes from 4200 to 18000 rpms, is that what you really cut at. We didn't want to lose any more bits testing.

2.Also our CNC doesn't squirt out coolant and we were wondering what to buy as an add on for it. Kinda like a mister that plugs into a compressor???

3. Also what coolant to buy, cutting aluminum, carbon fiber and plastic at the moment (mcmaster carr would be great)

Thanks in Advance,

http://www.techno-isel.com/CNC_route...C_Tabletop.htm

Re: CNC Router/Mill
 

If the spindle and ways are in good condition, that's probably a fair price based on what I've seen them go for on Ebay.