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View Full Version : CNC Mill - Where to begin?



Bryan Cowan
04-04-2008, 5:22 PM
I understand this is a woodworker's forum, but hopefully someone (or many) can point me in the right direction.

I currently work with 24" x 24" sheets of 1/8" aluminum. I take stencils and marker them on the sheet. I proceed to use a bench-top bandsaw with a metal blade and manuever around the outline to cut out my shapes. Let's put it this way; no two pieces are ever the same...big sheet of metal + small bandsaw table = balancing act.

I then take those cut-out shapes to a drill press to drill 1/4" holes straight through.

I would love to be able to put these 24" x 24" sheets into a machine that would mill the holes and cut out the shapes.

Can anyone point me in a direction that could minimize all the manual labor I put myself through? :)

Thanks :D

Kenneth Hertzog
04-04-2008, 7:13 PM
Bryan

the more the manual labor goes away the cash also goes.
with that said
you will need the following.

computer ( that will run the lastest programs )
a cad-cam program that generates G-Code
and a CNC machine


if you got questions ask away

been doing this for 6 yrs now.

ken

Bryan Cowan
04-04-2008, 7:30 PM
Bryan

the more the manual labor goes away the cash also goes.
with that said
you will need the following.

computer ( that will run the lastest programs )
a cad-cam program that generates G-Code
and a CNC machine


if you got questions ask away

been doing this for 6 yrs now.

ken

The less time I spend in the garage, the happier my fiancee will be :)

I've dabbled in CNC work before while attending a University and am familiar enough with G- and M-codes that I'll be comfortable enough in the work I need to do.

My main/biggest question is what sort of CNC machine should I be looking for? My needs for this machine is to drill and cut 24" x 24" x 1/8" sheets of aluminum. I can make the sheets smaller, if necessary, because of restricted CNC table size. I've chosen 24" x 24" because it is easy to handle and relatively inexpensive when compared to the amount of parts I can get from it.

Thanks Ken,
Bryan

Richard Rumancik
04-04-2008, 7:51 PM
Bryan, I suggest that for 1/8" alum you consider a router such as the K2 series at k2cnc.com. I have never actually use one of these but it may get you started. You can't use a regular mill very easily for 24" x 24" sheets as the tables are not that deep unless you go to a huge machine. The K2 website says that these machines are suitable for millling aluminum. Stay away from the MDF and plastic HDPE units you see on eBay. You need a rigid machine to mill aluminum.

For software take a look at the Vcarve products from Vectric. Like Vcarve Pro or Cut 2D, Cut 3D. If I was buying that's what I would look at getting . . .

You might also need a drawing program like AutoCad LT or similar. For simple shapes some people get by with Vcarve alone.

Bryan Cowan
04-04-2008, 8:23 PM
Richard,

There's nothing too complex about the parts I want to mill, but I do have AutoCAD if needed. I figured the biggest problem would be the size of alum sheet I use. I will research a K2 machine and see if it may be a viable option.

Should I consider any other CNC milling/routing machines?

Thanks,
Bryan

Kenneth Hertzog
04-04-2008, 8:58 PM
Speed is the factor
A wood working machine adapted to do metal is usually to fast
and a machine for metal is usually to slow.

that said is this a hobby or a serious business

A machine that accepts G code you can set the travel speed
if you get a router machine that you can set the spindle speed slow
enough and you have a .25 inch shank on the mill bit you could cut alum.

just a thought

isn't this confusing

ken

Richard Rumancik
04-04-2008, 9:04 PM
I was planning on buying a router a few years ago but stalled; I am getting interested in it again. The Vcarve software looks pretty interesting and the price is quite reasonable. For your parts, if you stay 2D only I think you can get by with a couple hundred dollars for the Cut2D software to create g code. That is a bargain in my opinion. I have a laser but it isn't the tool for every application.

If I think of any other machines that might be comparable to the K2 series I'll add it to this thread. I think some people have been milling on ShopBots and they do sell a small machine that might be suitable for your application.

Check out the Rockler thread on this page; Keith mentions the ShopBot PRSstandard BT32 Buddy that lists for $3,995. Talk to the ShopBot people and tell them your application to determine suitability.

Keith also posted an item on this page of a brass medallion being machined on a ShopBot (a larger one of course.)

Bryan Cowan
04-04-2008, 9:15 PM
This CNC machine will be used in a small business, but only operated maybe 15 hours or less per week.

I will drill the sheets first, then cut the individual plates. The CNC machine will replace the bandsaw and the drill press and A LOT of time.

Steve knight
04-04-2008, 10:57 PM
a shopbot will do it. You need to take light passes and use air cooling on the bit to keep the aluminum from sticking to the bit. for a clean cuts a onsrud O flute bit works about the best. I haven to cut much aluminum yet but I have the air cooling to do it.

Bryan Cowan
04-04-2008, 11:04 PM
I have emailed both K2 and Shopbot asking them what they recommend via their product line. Since it's the weekend, I doubt I will hear from either until early next week.

Any other companies I should contact?

Steve knight
04-04-2008, 11:17 PM
I have emailed both K2 and Shopbot asking them what they recommend via their product line. Since it's the weekend, I doubt I will hear from either until early next week.

Any other companies I should contact?
it' better to call shopbot their spam filters catch too much. the buddy would be a good choice for you. keeps the price down and the size.

Bryan Cowan
04-05-2008, 12:02 AM
I believe there were a few "Buddy" systems? As I'm new to this somewhat, how would these machines cut the plates? If the 24" x 24" sheet of aluminum is laying flat on the table, how could the machine physically cut through the aluminum without damaging the table surface?

Steve knight
04-05-2008, 12:12 AM
what you would buy is the size you need. if you can afford it and have space you want to get as big of a cnc machine as you can because you will find for more uses for it as you learn about it.
the table surface is called a spoilboard it is designed to be cut into and replaced. but you can cut just to the surface too. mine gets rally hacked up in use. then you just plane the surface off with a large bit and it is fresh again.

Bryan Cowan
04-05-2008, 12:21 AM
100% of the pieces I cut come from that 24" x 24" sheet of aluminum. Right now, I see no other use for the CNC machine other than combining the drilling and cutting in one process.

I always wondered how you cut through something and what happens to the table. I guess I will learn more about it if I commit to a CNC machine.

Steve knight
04-05-2008, 12:27 AM
you will be surprised what you can do with the machine. it is the most useful tool a person can have. it can do whatever you can figurer out how to make. check out a few things http://tinyurl.com/2w5szn

Richard Rumancik
04-05-2008, 12:28 AM
You will also need to figure out a clamping strategy. One possibility is to clamp the edges to the spoilboard, then use very small bridges (tabs) on the perimeter of the part outline to keep them stuck in the sheet till the entire sheet is done. CNC punch presses often use a similar strategy. Using this method will leave a burr when you pop out the parts so you would need to clean up the tab. Vcarve can generate the tabs you need automatically (it could cut through half the material thickness if you wanted.)

Other options are vacuum hold down and adhesive tapes. Or possibly you could drill the holes, then put a couple screws through the holes into the spoilboard to hold it in place. The holes would always land in the same place. With an electric screwdriver this might be feasible. Maybe there are other options.

Steve knight
04-05-2008, 12:31 AM
vcarve software is pretty good. it's not a super great cad program but it is far easier to sue then most packages out there. I have done some pretty cool things with it. it's cool that shopbot bundles it with their bots now.

Bryan Cowan
04-05-2008, 10:19 AM
Step 1: Find a decent CNC machine to do the job first :)
Step 2: Figure out how to work it correctly, lol

I'm sure when it comes to that point where I have this machine in the garage scratching my head, I'll be back to ask "hey, what now?" :)

I've priced outsourcing these plates to local machine shops and I wasn't satisfied with what they gave me. In fact, their bids were so high, I could buy my own desktop CNC machine and have it paid off in under a year had I decided to outsource.

Steve knight
04-05-2008, 3:07 PM
buying the right machine is not so bad learning to sue it is the hard part. cnc has a steep learning curve but it has the most rewards too. I spend a lot of time playing around and trying new things.

Leo Voisine
04-06-2008, 10:17 PM
I will go along with the rest of the group here.

CNC router. You did say sheet ALUMINUM right.

Aluminum is east to cut.

Used CNC machines are somewhat reasonably cost effective.

You can do all the profiles AND the holes. Use about 1/4 diameter end mill.

Vacuum clamping if at all possible. If not then tiny tabs, and clamp on the edges of the sheet stock.

VCarve Pro is a REAL good choice in software.

George D Gabert
04-07-2008, 4:20 PM
another suggestion is to try to plasma cut the parts. people like torchmate and plasma cam make tables the size you need. The software for the plasma cam handles converting the DXF file into their machine. The plasma torch comes from the local welding supply house. They will be able to tell you the utility requirements (shop air, electrical)

We use plasma to cut 1/2" carbon and stainless steel. since your shapes are not to complex the edge finish should not be a problem.

This solution also solves your hold down challenges as there is nor tooling force acting on the material.

Regards
GDG

Bryan Cowan
04-07-2008, 4:40 PM
another suggestion is to try to plasma cut the parts. people like torchmate and plasma cam make tables the size you need. The software for the plasma cam handles converting the DXF file into their machine. The plasma torch comes from the local welding supply house. They will be able to tell you the utility requirements (shop air, electrical)

We use plasma to cut 1/2" carbon and stainless steel. since your shapes are not to complex the edge finish should not be a problem.

This solution also solves your hold down challenges as there is nor tooling force acting on the material.

Regards
GDG

I can only begin to imagine how much that setup would cost?

George D Gabert
04-07-2008, 5:18 PM
I am not sure, but I think a friend put 1 in his garage for about 5 - 7 K, several years ago, for a 48 x 48 table and enough power to cut 3/8" carbon steel.

We have cut sign as big as 48 x 120 by indexing the part on the table.

I think he had the shop air and computer already.

Ron McAllister
04-09-2008, 2:52 AM
HAAS CNC mills are quite remarkable. I've been around these mills in action. I worked in a CNC shop and programmed and ran Hardinge CNC lathes. HAAS makes smaller single phase mills for small shops. Also you might check with Torchmate. They make CNC machines that cut with a small variety of either gas, plasma or even router versions of machines that operate on a platform as small as 4'X4' tables using a laptop computer.