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Greg Parent
09-24-2003, 10:26 AM
I need to produce 50 pieces of wood all the same shape. They are rather complex but I think it can be done on a mill with a CNC setup.
Is it possible to mill cedar planks on a CNC metal mill without undue modifications, causing any damage,etc?
I am going to approach a local machine shop and would like to have a little more knowledge concerning commercial operations. Is moving to wood from metal going to cause them alot of problems? Will I be charged for extra setup costs because it is wood and not the normal metal?
Thanks for your help.
Greg

DR
09-24-2003, 11:18 AM
Metal working machines do a good job cutting wood in some cases. Cleanup after the job can be a major issue. The wood dust has a tendency to coat all the lubed surfaces of the machine. Cedar is especially nasty in my experience because of the dust.

Hard to say what kind of response you'll get from the shop owner. I've cut exotic hardwoods on my CNC's for customers. I kind of liked the jobs even with the cleanup because the material cuts so easily compared to metal.

You'll probably be charged on a time basis, with a little more than usual cleanup costs.

BFHAMR
09-24-2003, 11:19 AM
Greg,

You might try a pattern shop. They frequently cut wood, steel, aluminum, plastic and other materials on the same CNC machine.


Dan

Stepside
09-24-2003, 12:19 PM
Find someone with a CNC router. You might find one at a large sign shop.
I have cut wood on my CNC by mounting a router on the Z axis. The 5000 RPM of the mill wasn't fast enough to produce a clean cut. The speed of a trim router worked just fine. I didn't even have to sand afterwards. BUT it was a real bitch to clean up all the dust wherever there was even a drop of oil.

Evan
09-24-2003, 12:41 PM
When I built my telescope I needed a 9" faceplate to make some 9" alum rings. I used 1" thick high density particle board screwed to a stub of 4"x4" in the four jaw. I trued and faced off the particle board disc which generated a lot of dust. Ended up taping the nozzle of the shop vac to the tool post which mostly eliminated the dust problem.

Alistair Hosie
09-24-2003, 04:51 PM
I dont think turning wood on a metal lathe cnc or otherwise is a short term problem but I would not advise it in the long term as shavings/dust are bound to get into the bearings eventually and will be nigh impossible to remove.Perhaps cnc equipment is capable of avoiding this regarding their bearings etc but I doubt it.I have an elderly friend who had a large metal cutting lathe and used it almost exclusively for wood the results to my mind were always second best although he overcome this with a deal of sanding while under power his attitiude was that it his age even if the lathe did pack in it would still probably outlive him and as he said you can't take the old girl with you can you? http://bbs.homeshopmachinist.net//biggrin.gif http://bbs.homeshopmachinist.net//biggrin.gif http://bbs.homeshopmachinist.net//biggrin.gif good luck I think the advise about the cnc router is best route for you regards Alistair

jstinem
09-24-2003, 04:55 PM
Try a architeural millwork shop or a furniture repair shop. If the shape is 2d they won't any problem knocking out 50 pieces for you. They will know to make the quickest and cheapest forms to guide the stock. Its what these guys live for. I know... I used to be one of them.
Joe

DR
09-24-2003, 08:26 PM
<font face="Verdana, Arial" size="2">Originally posted by Alistair Hosie:
I dont think turning wood on a metal lathe cnc or otherwise is a short term problem but I would not advise it in the long term as shavings/dust are bound to get into the bearings eventually and will be nigh impossible to remove.Perhaps cnc equipment is capable of avoiding this regarding their bearings etc but I doubt it.I have an elderly friend who had a large metal cutting lathe and used it almost exclusively for wood the results to my mind were always second best although he overcome this with a deal of sanding while under power his attitiude was that it his age even if the lathe did pack in it would still probably outlive him and as he said you can't take the old girl with you can you? http://bbs.homeshopmachinist.net//biggrin.gif http://bbs.homeshopmachinist.net//biggrin.gif http://bbs.homeshopmachinist.net//biggrin.gif good luck I think the advise about the cnc router is best route for you regards Alistair</font>

FWIW, I know several stringed instrument makers on the west coast who use Fadal CNC mills to cut wood. Fadal warrantees the machines even though they're used for wood working (dust and all).

There're a number of reasons for using a metal cutting machine instead of a CNC router.....Many of the routers are foreign made with unsupported brands of controllers. More bang for the buck with a metal cutting tool. Automatic tool changers are "standard" on metal cutting machines.
The list goes on......unless I was cutting very large sheet goods I wouldn't even consider a CNC router over a milling machine.

mpbush
09-24-2003, 09:04 PM
You will have to REALLY watch the direction of both the cutter and the grain of the wood. Expect to have to reprogram some of the cuts so that the order and direction of cuts results in clean cuts.

For example, in cutting a rectangle, cut the end grain first, that way the cuts with the grain will remove the inevitable tearout.

If you have any questions, please feel free to ask me.

Michael

spope14
09-24-2003, 10:15 PM
Michael is right about the end grain comment. I do this as a rule being a woodworker, and knowing about "block planing" the ends of a piece. have always done this as a habit, never thought to write it until now.

Wood cutting on machines can be a double edged sword. The machine iron itself will not necessarily suffer from wood dust as an abrasive. However, it is a good idea to clean and oil the wipers before and after cutting wood in major quantities. Clean wipers with kerosene, dry, then put way oil in them. This keeps corruption out from under "slide surfaces". Keep bearing areas very clean around them, even sealing housings or covering "lay surfaces" with something in the area such as saran if you do much of this.

Wood can gum machines over time, but not badly if the machine is oiled. However, wood can also act as a carrier for grits, stock coatings (the hot rolled surface and cold rolled surface) and other abrasives as they tend to stick with the wood particles and not to be flushed out by regular oils as easily as the wood particulates tend to gum to items as oil actually helps it do so. I have cleaned many a machine used in wood / metal combination cutting and found this to be the case. Wood alone does not tend to do this.

As for CNC, or with DRO's and fan situations, you have to be careful when cutting wood. Lots of dust. Lots of dust sucked into controls. I have seen control panels and fans overheat and filters fill quickly due to dust, and switches get a bit dusted and gummed over time. I cut wood and high density foam on a regular basis, and keep a vaccuum - dust collector near the cuts to keep this down to a bare minimum. Also use the same to clean ASAP after the wood chips get a bit deep. The dust collector is also vital in fire prevention as the little chips - dust fly around, and eventually can be a problem. On my CNC control, the front panel is that "bubble front" type of thing, but the rear cooling fan is close to the work area. I used a dryer hose hooked to the fan, and ran the hose behind the machine, far from the work area as an air collection area, thus isolating wood dust out of the filters and control panels.

DRO's, clean out any vents ASAP and often with a shop vac, but watch out for "static' that can develop and blow it all out - same with CNC. Use GROUNDED vacs and collectors, and be sure to touch off on an independent metal surface often least you blow a control. Unlikely, yes, but one chance in 1000, leaves 999 good experiences, the one leaves a hell of a bill.

On manual, common sense, oiling, good cleaning, and Preventative maintenance.

The difference between metal and wood machines is the lube applications. A good woodworker uses something akin to "bowling alley wax" on machines to keep them "slick', but us metal heads use oils, which tend to collect the dust.

Just my humble opinions and experiences.

[This message has been edited by spope14 (edited 09-24-2003).]

firbikrhd1
09-24-2003, 11:31 PM
Anybody tried out one of the Grizzly Woodmills, G9977? During my quest for a mill I came across it and think it might be worth considering for metalwork with a 1750 RPM motor. Unlike Grizzly's other machines, it has a hardened table and ways. I just don't know how that hole in the table for drilling would affect it's usefulness for metal projects.

DR
09-25-2003, 01:50 AM
<font face="Verdana, Arial" size="2">Originally posted by mpbush:
You will have to REALLY watch the direction of both the cutter and the grain of the wood. Expect to have to reprogram some of the cuts so that the order and direction of cuts results in clean cuts.

For example, in cutting a rectangle, cut the end grain first, that way the cuts with the grain will remove the inevitable tearout.

If you have any questions, please feel free to ask me.

Michael</font>

Using CNC machine tools it's not been my experience or of my customers that grain direction is the problem it is with conventional woodworking machines. Using high rpm, segmented, high helix carbide with a climb cut we seem to be able to zip around the contours with very little concern for grain direction.

I've been pleasantly surprised by how well our machines do in wood. I attribute it to the CNC machine's rigidity.

Greg Parent
09-25-2003, 01:06 PM
Hello everyone,
Thanks for all the information. I feel much better going in armed with some background to the potential problems.
Now to find someone who wants the work.
Thanks again.
Greg Parent

Alistair Hosie
09-25-2003, 01:32 PM
Dr as said my main concern ws with the bearings and as I pointed out I was not sure whether this was a problem with CNC machines however as you have said it is not a problem then that must be correct,As I have no experience with these.I can only tell you all of the books I have read point out that to be wary of this however on standard metal lathes but obviously c n c is different as I said I am not sure,but glad to learn that this is no problem.Alistair