Metal cutting techniques..

[billp]

I've started a new "thread"simply about metal because it seems that there are more and more people (including myself) who are getting jobs that in some way involve materials such as aluminum, brass, stainless, etc. Most of us do not have a plasma cutter so we'll be trying to work with the router we use for our everyday kind of jobs..
I have a customer who has asked me what Shopbot's capabilities are regarding the cutting of brass. I have searched the Forum history and found a few mentions of the process, but nothing in any depth yet. My customer's question is;what thickness of brass sheet could he give me to cut with my PC 3-1/4 hp router? He normally works between .020-.050 and wanted to know if I could do that with a "clean"edge. I have never tried it, so I need some feedback from those of you who have.
What kind of bits work better (1,2,3 flutes, straight versus spirals, etc.)?.Is misting a necessity with brass? Do I have to keep my feed speeds very slow? etc. I haven't committed to any job with this customer yet because I first wanted to see if it was going to be a major pain, but I'd like to at least have some guidelines for future reference as well. If anyone out there can add some insight I'd appreciate it. TIA, Bill P.

[Mayo]

I have had experience cutting a material with the brand name of Chemetal. The surface looked like brushed stainless but I think the composition was actually brass, judging from the edge color and the chips.

It was laminated onto MDF panels and the thickness of the Chemetal itself was probably around .025.

I was able to get a perfect edge using a brand new 1/8" two flute straight bit and a 1/16" straight bit. I did not use any misting. My cutting speed was .5

The only problem I had was on a test cut of some 1.25" lower case letters. The Chemetal popped off of the MDF it was laminated to, in the center of a couple letters like a "d" or an "o". This was a lamination problem rather than a cutting problem though. Since the material was supplied to me already laminated, I had no control over that.

The actual job involved much larger letters - as you will see from the photo at http://www.designcutters.com/B2BilT.jpg
This was one of the first paying jobs I did on the ShopBot and it really wracked my brain trying to figure out how to do it without ruining the customers material. Two separate panels, one with a wood background and one with the Chemetal background. Wood letters were cut from birch plywood and inlaid into the Chemetal background, and Chemetal letters were routed and inlaid into the wood background. Of course the customer supplied two different thicknesses of material that the letters were cut from, just to keep things interesting. This meant that the female shapes routed into the backgrounds were different depths on each panel, so that the inserted letters would be flush with the surface. The photo shows the letters placed in position but not fully inserted, because the customer was going to first stain the wood background.

If you have to cut material that thin without it being laminated to something thicker, I think you'll have two problems. 1. Keeping the material from moving while you cut it. You could try double sided carpet tape or spray glue if you don't have a vacuum system that will handle small pieces. 2. Removing the material that has been cut. Brass is fairly easy to bend when it's that thin. How to remove it from the table without bending it might be a challenge.

My only other caution would be, WEAR EYE PROTECTION. The little chips of brass flying through the air could cause some serious eye damage.

[billp]

Mayo, great info, thanks for all the tips!

[sheldon@dingwallguitars.com]

Bill,

I have machined a fair amount of .025" brass shim stock on a pin router using carbide straight flute router bits and bearing guided trim bits. I've also done one run on my Shopbot using a high speed spindle and a 2mm bit.

Using the pin router dry, there was always a very large burr that had to be dealt with even though the material was held on both sides flush with the cut.

I found I got a much smaller burr using the high speed spindle and 2mm bit and lubricating with a parafin based bicycle chain lube. The chain lube was the only thing that didn't get blown away from the cut before it had a chance to do any good. The burr was easily removed with a buffing wheel (It's an internal part so shiny edges aren't a problem). A scotchbrite wheel would probably work just as well.

If it's possible to get a burr free cut in brass, I'd sure like to hear about it.

[kaaboom_99]

Hi Gang!! Just thought I would pop in and see how things are going. As I am sure you all agree, I HATE THIS D**N LEARNING CURVE!!! I just want to make nice things as quickly and effortlessly as possible. (Yeah, I am lazy. Too many other projects on the go.) Just to give you friends an idea what I have been doing with my machine (since I have had it a whole 60 days.) I have made every mount, bracket and clamp for the Shopbot, with the Shopbot. I have a PRT96. I made a 'T' slot table for clamping. I made some "hold downs" out of 1" x 2" oak. I cut and use the one hole dust collector. I have made a universal mounting system for the (4) tools that I presently use in my SB. These consist of a 3/4hp Ryobi Router - because I had one, a "Roto-Zip" I got for Christmas, a "Dremel" tool and a swivel head knife. Some projects I have worked on in my spare time (considering I am the father of 3 boys: 15, 12, 10, I work usually between 68 and 84 hours per week at my regular job, I also am a sound/lighting technician at our church and we meet 2 times a week and "twice on Sundays"). Sorry to diverse. Back to projects. I cut about every 10 days for my wife, "paper dolls" She is a member of a nation wide swap of paper cutouts. So she gets her images into CorelDraw, traces them and then I take over. We are talking very small pieces she used to do by hand for 30 - 50 correspondants. I have made a few "Gobos" - stencils to be placed in front of a flood light to project a lighted outline and made out of brass shim shock. This is done for the church. I have right now some 1/8" x 4" x 24" steel that is half finished being machined for a local pyrotechnics company for a protoype of a new mortar rack (tubes that hold the fireworks shells). Anyways having said all this I would like to offer anyone who would like (or if I can post it on the ftp site) a group (4) .sbp files I wrote/ modified to zero out all three of my axis while working on steel. It works well. Example. Cutting the first run of the 1/8" steel for the prototypes, I wrongly chose to use the underpowered Rotozip tool. Halfway through the cut I decided to change to the 3/4 hp router. No problem. Change tools and ran my zeroing routine and placed the bit right back into the same cut.
If you wish a copy of this, it is yours for the asking. I also wrote a quick file to vacuum my table, a file to park my SB - my SB sits in my basement. I had to knock out 2 walls to get it in. Consequently, I did not have the height for the plastic wire raceway to be routed above, It is routed horizontally - parallel to the table top. This is the reason for a "Park" file. Enough said. Love the forum. One of the key reason I chose Shopbot over a competitor!
Let keep it alive.

[tucker-52@charter.net]

Perry,

Why did you have to knock down two walls to get your SB96 into your basement? Lack of external entrance? Were the walls just in the way of your set-up? Were you good with computers before you purchased your SB, or are you "flying by the seat of your pants?" (Like I will be) Just curious.

Mark

[kaaboom_99]

HI Mark. No the SB comes delivered in peices. I knocked out the walls because of the footprint (the area) that the SB takes up. Yes I have a fairly good grasp of basic programming & computer troubleshooting skills. I am a liscenced electrician (15 yrs), an electronics technician and prior to apprenticing for the electrical trade I was a tool and die apprentice for 1 year. As far as "flying by the seat of my pants", as this is a new venture with only this forum as my mainstay of knowledge, my answer would have to be yes!

I like to be busy, challenged and want to be independantly wealthy (look again at my LAST name....)
So I am reading into this post of yours that you are soon to be purchasing a Shopbot. What did you order. Any add ons? What is you intention for its use, what industry? Hope to hear from you again>
Perry

[tucker-52@charter.net]

Hey, Perry. I'll soon be ordering a PRT96. I'll be setting it up in a basement area as well, (my Mom's) and thats why I was curious. Any noise problems, Dude? I mean, upstairs?

I've had a lot of good advice and help on this forum, and that's why I'm going ShopBot as well.
The folks on here are great, and so are the people at ShopBot. I would like to say Dianne Reynolds especially.

My computer skills need a lot of work, but I'm not going to let that scare me. At this point, it's kinda like jumping off a cliff. Fly, or crash.

No particular add-ons. Gonna go with a 110v router, probably with a Porter Cable 3.25. I had my mind made up that I had to have the $3,725.00 Columbo spindle, but the good people on this forum swaded me. I can always get that later, if I just gotta have it.

I intend to use my machine to service smaller Sign and Cabinet shops that do not have a CNC, as well as to make some wild ideas for arts and crafts
for myself to sell. I'm an artist and a craftsman,
and for the things I like to do, a ShopBot makes the perfect marriage for combining the two.

Ok, I looked again at your last name. I'll bet you that a year or two from now you'll be signing into this forum as "Verry Riche"!!!

Good Luck, and I'll be around. (Looking for help, no doubt!)

Mark

[Curt Bartel]

Hi Mark,

I received my prt96 almost exactly 1 year ago. When I ordered it in Oct/Nov 2000 it was approximately a 3 month wait to receive it. This was a good thing because it gave me time to set up a room in my basement also. What I did was to frame up 2x4 walls around my new workshop area, had an electrician do the wiring, and then I insulated the walls with r-13 insulation. I insulated the ceiling with 10" fiberglass batts( I could have done more, I have 18" floor trusses for my joists). Then I put 5/8" firecode sheetrock around the room.

I bought a window( one that a local lumber yard was stuck with from a special order) and have that between my computer room and workshop so that I can see what the machine is doing without having to worry about my computer getting full of dust.

My room is pretty well sealed for sound and dust and hopefully fire. I put in 3 exterior steel doors in the workshop, 1 between the office , a double door between my workshop and my rec room, and 1 that leads to a stairway up to my garage. I have an open stairway leading to my basement and my workshop is located under the opposite end of my house from our bedrooms. Sound has not been a factor at all, if it was my wife would let me know about it.

90% of the time I run my shopbot at night when everyone is sleeping (I have a 3 and a 5 year old) and have yet to wake anyone up. From upstairs the sound is a faint humming (Almost like someone is vacuuming in my basement behind closed doors)

I have the 3.25 variable speed porter cable and when I am doing the 3-d tif images I set it on its lowest speed and cannot hear it at all from upstairs.

I have the shopbot hooked up to an old craftsman shop-vac. When I am in the workshop it is hard to tell which is louder the shopvac or the router.

The dust that gets out of the room seems to be very minimal, the exterior doors are weather sealed and the only dust that seems to get out is the dust that hitchhikes out on my clothes.

The Shopbot is a part-time thing (5-10 hours a week) but I have been getting busier with it now that word has got out what it will do. I am a full time carpenter and have found that making things for builders is going to be my most profitable avenue.

Good luck,
Curt Bartel
Bartel's Wood Graphics LLC

[tucker-52@charter.net]

Hi Curt,

You waited 3 months for delivery? Is that normal?

Mark