Spindle ShopBot Desktop: Engraving & Cutting AL & SS

[WoodMarvels.com]

Hi guys, I want to start using my ShopBot Desktop (with spindle) to engrave and cut both AL and 304SS but have a few questions.

I'd glue the AL block using http://www.findtape.com/product190/Permacel-P-02-Double-Coated-Kraft-Paper-Tape.aspx?idx=10&tid=25&info=permacel the AL to 3/16 tempered Masonite with a Onsrud 63-625 bit. Pass depth: .025 Feed rate: 1 ips RPM: 14k

Question 1: what grade AL is best? I want to basically do the same as Jack found in this Youtube video https://www.youtube.com/watch?v=8_A53GpOP5w to make dies for my hot press machine. I went through the forum search and it seems to jump from grade to grade. Ideally, I'd also like to cut the blank out using the ShopBot as well (with tabs).

Question 2: I'm using partworks, is that good enough for creating tool paths for this stuff or am I better off upgrade to Aspire3D for more accurate toolpaths and less broken bits?

Question 3: I'd have some signage to do in 304 stainless steel, what bit would be best for that? I'd paint fill and seal after the words are engraved into it.

Thanks!
Jon

[tlempicke]

Partworks and Aspire will give you the same accuracy. The key to the whole thing is speed and feed rate. .025 sounds a bit aggressive to me. I would start with .012 and work up. Shopbot has a video about cutting Aluminum that should get you started. Just got a great tip on this at the McGrew Aspire camp in Columbia. Feel the chips flying off the bit with your hand. They should be hot! After completing a cut you should be able to touch the bit without discomfort. (Especially if you remember to turn off the spindle!)

Better study up on aluminum before committing to anything. 6061 (I think) is pretty commonly used. Many of the alloys are very difficult to machine (Translate that to broken bits and frustration)

I don't know that you are going to machine Stainless on a Shopbot. That stuff comes in, literally, dozens of alloys. even an experienced machinist in a normal metal working shop can have problems cutting that stuff.

[WoodMarvels.com]

Thanks Tom, will get some 6061 blocks and see how it goes, should get my bits in the mail in about a week. 50$/bit isn't like playing around with the 8$ wood ones I'm use to so going slow till I get my settings dialed in! Was hoping to use rubber engraved with my Trotec Speedy 400 flexx laser as it's way faster but the results on the foil hot press machine just aren't very good. AL is really the best, half the price from magnesium.

Jon

[donek]

The most common recommendation on pass depth is 0.05in
The best finish feed rate is 1.2 in per second
I rough cut at 2 in per second
I've run lots of 6061 and 7075. Both machine very well. Unless your parts must be very strong, 7075 is a bit overkill and pricey. All the aluminum parts in these items are machined on our shopbots:
http://www.donek.com/accessories/plate-system/a-plate/
http://www.donek.com/accessories/plate-system/af-plate/
http://www.donek.com/accessories/plate-system/f-plate/
http://www.donek.com/accessories/plate-system/bx-plate/

[coryatjohn]

I like 6061 and have cut it many times. It's a mean cut though and the key is aggressive hold down. AL fights back a heck of a lot more than wood or plastic. With items of really close tolerance, I always calculate in a deflection parameter. The bits bend when cutting, especially small ones like 1/8" so if you don't add in that value, your parts will come out too tight. Holes will be too small. Posts will be too large. Nothing will fit.

What hot press machine are you using? I'm looking for that type of machine to make small plastic parts and machine the tooling with my SB as well.

[WoodMarvels.com]

Very impressive Sean, are you doing it just raw or misting it with lubricant?

John, I have a small machine I bought in Vegas a few months back, was hoping to make my own dies with rubber but the results are just awful as mentioned... I want to make my own dies for this machine and I can with the ShopBot Desktop now that I know what grade and bits etc. to use. Picture here

http://cncroi.com/services/custom-stamping-mold-production/

Customer support for this stamping machine is just as awful as the results I'm getting using high temp rubber to foil stamp. BTW John, the ShopBot you have is the one I hope to upgrade to soon enough! How's the Alpha going?

Jon

[donek]

Everything is cut dry. I have on occaision used an air hose blowing on the cutter to cool it, but that's it.

If you are trying to make a branding stamp, the simplest and cheapest approach is to purchase a hot plate (http://www.amazon.com/Toastess-THP-517-Electric-Single-Coil-Stainless/dp/B002PBJ9F4/ref=sr_1_22?s=kitchen&ie=UTF8&qid=1430679643&sr=1-22&keywords=hot+plate) and screw your brand to the heating element. It is possible to melt a 6061 aluminum brand if left unattended, but as long as you continue stamping and turn the element off as soon as you are done, you should be good.

[coryatjohn]

>> BTW John, the ShopBot you have is the one I hope to upgrade to soon enough! How's the Alpha going?

As I have nothing to compare it to (my first bot), all I can say is it does what I want and I have no complaints.

[WoodMarvels.com]

Any suggestion regarding a smaller bit? I got a shipment of 4 Onsrud 63-625 and those are big which is fine for cutting but not fine details I'm hoping to achieve.

Jon

[coryatjohn]

I've used single flute 1/8" bits for aluminum with pretty good success but one thing you have to consider: The smaller diameter the bit, the larger the deflection. When doing things with little tolerance for error, this is pretty important to consider.