CNC cutting services?

[Bruce Johnson]

I'm the one that suggested the trick with the printed stickers. I use it on some of my metal parts, as a quick way to put down consistent layout lines.

There are lots of old-fashioned ways to cut out parts and trim them to size accurately. You don't need CNC or expensive machinery. I haven't seen the laminate part you're working with, but here's a quick pass at a process:
1.) Hold an aluminum template on the part and scribe around it to establish layout lines OR use a printed sticker.
2.) Saw the part out to the basic shape with a small bandsaw (with a fine tooth metal cutting blade) or by hand with a coping saw.
3.) Trim the ends to the final size against a belt sander, or with a file, checking the size using an aluminum gauge.

With some care making up your gauges and some practice, you can make up parts to a repeatable accurate size, and it really doesn't take very long.

[Bruce Johnson]

The best sander for this work is a little 1" x 42" belt from Rockwell. You see them on CL from time to time. You could also look for a Dewalt scroll saw if you want to speed things up (and blow some dough).

Yes, those small 1" x 42" or 1" x 30" belt sanders are handy for fine trimming of parts. I have several of them in my shop, as well as much bigger ones too.

I don't recommend buying a scroll saw. I have a nice Delta and a Ryobi, and I've found them to be useless for almost anything. Spend your money instead on a small tabletop bandsaw. Even the little ones can be very handy for trimming out metal and plastic parts (with the right blade!).

[David Schwab]

I have a benchtop 4" X 36" bent sander with a 6" disk. I use that for all my blade shaping.

[FunkyKikuchiyo]

I have the same sort of belt sander that David mentions. It works great, but if I do lots of metal on it, I'll chew through paper like crazy. Also, the table the came with it for the disk is nearly useless. Ryobi doesn't see much need in truing those things up I guess... plus, that set screw to hold the angle slips, so if I find a position I like, it may change on me. No good. It sits permanently detached. I've thought about trying to fix it, but I guess I'm a machinist only be default and tend to dread those sorts of jobs. That is part of why I was looking as something like an oscillating drum sander - seems like an odd choice, but those tables are great to work on, and I'll have to round those edges at some point, too. Also, I can use it for the bottoms of strat nuts! I'm sick of using the edge of my belt sander for that.

I've seen those longer belt sanders around and they look neat, but are they really that strong?

And, will a band saw really chew through the metal? Wouldn't I need a larger, industrial one? I was looking at the large cut off saws, but I really don't know what'll much through it. I have a table top band saw, but the thing is in desperate need of attention and I very rarely use it. Will it rip through 12" of my material?

Harbor Freight sells those little tool grinders for not a lot of money. Anyone have experience with them? I figure if I can do rough stuff with those, it'll pay for itself in saved sandpaper pretty quickly.

The material is about .078" thick, comes in 12" x 8" sheets (give or take) and is mostly comprised of low carbon steel.

Thanks everyone - you're doing a pretty good job of talking me out of CNC work. I had to go CNC for the other flatwork (over-designed, methinks), so I was just following that train of thought to get it all done.

[David King]

Bandsaw blades come in every description but the benchtop saws will limit your choices to those with thinner blade-stock that can get around the smaller wheels without work-hardening and developing cracks over time. You want "bi-metal" blades in .020" by 3/16" or 1/4" stock if they exist. Starrett might just make such a blade but it will be pricey. You'll probably only find .025 and .032 bi-metal which is meant to run on 14" and larger wheels. You'll need to slow the saw way down for steel (300-600 fpm) and you want LOTs of teeth per inch, say 18-20 tpi. Don't forget lube/ cutting oil.

The 1 x 42 belt sanders are industrial grade machines with 1 HP and designed for shaping steel and grinding welds. They can blow through that thin sheet metal like butter

[FunkyKikuchiyo]

That's some great information. I'd seen those sanders around and had wondered what they would work for. I'll start researching those.

I'm not sure if I have the workshop real estate for a big bandsaw (though I'm jonesing for one like you wouldn't believe)... I know David Schwab (IIRC) uses the cut off saws sometimes, like the cheap Harbor Freight units. Do you do sheets David S, or just bar stock? I wonder if, carefully used, that would crank through these sheets? I wouldn't need to cut with great precision - just cut out squares that I can shape on a sander/grinder.

And speaking of grinders, you don't seem to be suggesting them directly David K, favoring sanding. That seems a little counter intuitive to me. The appeal of a grinder to me is 1) the wheels presumably will last longer than the equivalent $$ worth of sandpaper, 2) less scratch removal, and 3) I can put a buffing wheel on the same arbor. Am I needlessly stuck on that idea?

[David King]

The problem with grinders is that their grit gets all clogged up right away if you don't dress them constantly and then you need to keep them true and balanced. The narrow belts we are talking about are inexpensive in quantity and they are formulated to grind steel, not the over-priced woodworking crap they foist on basement handymen at the hardware store.

Try supergrit.com or klingspor: Abrasives From Klingspor's Woodworking Shop

For bandsaw blades you can look for Lenox Diemaster II 1/4" x .025" here Lenox Diemaster 2 Bandsaw Blade | Engineered for Contour Cutting - Spectrum Supply
I'd get a used 14" bandsaw or perhaps a 12". You'll then have to switch out the pulleys to get the speed down from 2600fps to say 600fps. Grizzly has cheap cast iron pulleys. If swapping pulleys ain't your thing you can pop a 3 phase motor on there and get a cheap VFD controller off ebay.

There are some tiny handheld metal cutting bandsaws from Porter Cable or you can pickup a floppy Harbor freight 4" x 6" metal cutting bandsaw for $150.

[David King]

If you are just cutting squares go to your local sheet metal shop and have them slice up all the material on a Pexto sheer. They can get you hundreds of squares or rectangles to .005" accuracy in a few minutes. There is a tool for the job and then there is the right tool for a job but you need to know what the job is first.

[FunkyKikuchiyo]

Thanks DK - I'll investigate my current bandsaw and see what size the wheel actually is - though I suspect I won't be able to slow it down mechanically. The handheld may be the way to go, if my metal working friends can't help me out. You've given great advice, but my budget has been munched down, so I feel like I should explore the options besides the bandsaw right now.

I also didn't mention that I do have a table saw AND a radial arm saw. I know some people will do softer metals on these saws with special blades, but would this steel stock be too much for it? I figured as such which is why I didn't bother mentioning it, but I figured it wouldn't hurt to throw that out there.

Thanks for the tips on the sandpaper, too. I do remember working with the blue-ish metal working papers and that they work pretty well, too. I can't believe the prices on those belts! I can't imagine how much money I'd be spending if I just did that through Home Despot.

[David Schwab]

And, will a band saw really chew through the metal? Wouldn't I need a larger, industrial one? I was looking at the large cut off saws, but I really don't know what'll much through it. I have a table top band saw, but the thing is in desperate need of attention and I very rarely use it. Will it rip through 12" of my material?

Harbor Freight sells those little tool grinders for not a lot of money. Anyone have experience with them? I figure if I can do rough stuff with those, it'll pay for itself in saved sandpaper pretty quickly.

The material is about .078" thick, comes in 12" x 8" sheets (give or take) and is mostly comprised of low carbon steel.

Bandsaws work fine with metal with the right blades and at a slow speed. As others have pointed out they make metal cutting band saws.

I use one of these to cut 1/8" thick low carbon steel bars to length to form into blades.

6" Cut-Off Saw

It cuts like butter. I set up a stop to get repeatable lengths, and then de-burr and finish them off on the belt sander. I mostly use the disk sander for that.

[FunkyKikuchiyo]

I did some research on my band-saw - it is a three wheel design and takes a 56 1/8" blade. I can't seem to find the speed anywhere, but I don't see how it could possibly be changed mechanically.

That cut off saw is tempting. I'd have to make half of a cut, flip it, then do the other half which could potentially get messy, but it is a small tool and entirely within my means. David K's advice is great (and bookmarked) but I'm not sure if it is practical for me right now.

1/8"? Really? That is impressive.

[defaced]

Depending on how much you love (or hate) your table saw, you can put abrasive blades on them and cut metal. This is not pretty, but I've done it. Also, depending on how good of a cut you need just to section the metal, angle grinders with a cut off wheel will work but are not by any means precise, and if you've never used one, pretty dangerous too. Something to consider if you choose to go the abrasive cutting route is the temperature at the cut. If your material is already laminated, I would avoid abrasive cutting, the leading edge of the cut can get red hot. I don't think that'd work very well for your materials.

Here's a part number for a band saw blade for your saw if you decide to go that route. Designed for cutting thin metal. Go to mcmaster.com, part number 4179A853.

[David Schwab]

That cut off saw is tempting. I'd have to make half of a cut, flip it, then do the other half which could potentially get messy

No you don't. I cut through 1" wide bars all the time. it would probably do wider as well, but that's the widest I ever use.

1/8"? Really?

Yep. I've done thicker as well.

[FunkyKikuchiyo]

No you don't. I cut through 1" wide bars all the time. it would probably do wider as well, but that's the widest I ever use.

I'm dealing with sheets that are 12" x 8". If push came to shove, I could laminate narrower pieces, but I was making these for a different style of tooling that has since gone out the window. I'm not sure how that would behave if I just dropped it straight onto one of those sheets - that is what I was getting at.

[David Schwab]

I'm dealing with sheets that are 12" x 8". If push came to shove, I could laminate narrower pieces, but I was making these for a different style of tooling that has since gone out the window. I'm not sure how that would behave if I just dropped it straight onto one of those sheets - that is what I was getting at.

I choose my pieces based on not having to do much machining. So I only have to cut them to length and do some shaping.

This is a cutoff saw, so it's made for cutting longer pieces to length. If you have to cut a piece of of a larger sheet, that wont work.