31
CamBam help (General usage) / Re: Machining Polycarbonate
« on: November 28, 2022, 04:20:36 am »
Lloyd beat me to the punch. I wholly agree with what he said in raising your work holding to limit your z-axis travel.
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32
CamBam help (General usage) / Re: Machining Polycarbonate
« on: November 27, 2022, 00:59:38 am »
Acrylic is nicer to mill in my experience (and compared to many on this forum I do not do nearly as much).
Quote
I’d probably need vacuum hold down if so.I strongly recommend you look into to using the "Green Frog Tape/Super-Glue" hold down method...it works wonderfully for many materials. It is described in recent threads (well, er, this year sometime).
33
CamBam help (General usage) / Re: Machining Polycarbonate
« on: November 26, 2022, 03:56:03 am »
Thanks, nice test Dave.
34
CamBam help (General usage) / Re: Machining Polycarbonate
« on: November 26, 2022, 02:31:15 am »
So, Dave, is the test you did a profile (edge) cut of the full thickness of this material?
It isn't clear to me, and there is no pun intended.
It isn't clear to me, and there is no pun intended.
35
CamBam help (General usage) / Re: Machining Polycarbonate
« on: November 25, 2022, 01:24:18 am »
What cutters and speed did you use?
The .25D cute was a low helix angle spiral which according to the manufacturer is designed for hard plastics, which may be the case but even though its upcut, probably doesn’t eject chips as well, especially on the two sided cut. I have a single O-flute cutter in that .25D which is supposed to be better, and thinking with a little shallower depth increment and more federate may do the trick dry.
The .031 cutter I was using to cut the logo is actually a single O-flute not round nose. I had to look at that thing under high magnification to confirm such.
My Porter Cable router 890 is my "spindle" and is modified to be controlled by a Super-PID speed controller. I've used this combination now for close to 9 years. https://www.vhipe.com/product-private/SuperPID-Home.htm.
My router also originally came with its own "dial" speed control in a similar rpm range like yours and could not go below 14K rpm either. With this PID controller it can now go down far further, like 5K rpm, under complete control by Mach3. My acrylic milling/engraving speeds are usually in the 10-12K range, feeds in the 30-45 ips range. The largest bit I use is a 1 or 2-flute .125". I've grown to prefer doing parts cut-outs using a .0625" diameter bit just to minimize stock waste, but have also used a .0313" 2-flute. If waste isn't a concern then I use a .125" 1 flute upcut bit. But my preference is a .0625" 1 flute, fish-tail with an .125" shank. I also use the same size in an upcut fish-tail, both with a .25" flute length. My depths of cuts are usually from half the diameter of the bit and occasionally up to the diameter of the bit. I buy bits that are expressly optimized for thermoplastics and get them from Think & Tinker, Ltd. in Colorado. Their website is https://www.precisebits.com/.
My machine is made from polyurethane'd MDO with the waste board made of polyurethane'd MDF, except for the worksurface. I've added the capability to use small amounts of liquid lubricant by screwing down a piece of HPDE, surfaced so it has about .125" raised edges, for a spoil board that's about 12" x 22". But for most of my acrylic milling and engraving I've not needed it.
Happy TurkeyDay!
36
CamBam help (General usage) / Re: Machining Polycarbonate
« on: November 24, 2022, 20:15:39 pm »
One possible reason liquid cooling may not be an option is that not everyone's machine is waterproof or even water splatter-proof.
I'm no expert but have done a lot of polycarbonate engraving and milling, relatively speaking.
If welding is occurring then that is an indication of high friction and heat. You're on the right path to increase your feed rate if you cannot decrease your spindle rpm. Also, large diameter mill bits will have a higher angular velocity than a much smaller bit for a given rpm.
I'm no expert but have done a lot of polycarbonate engraving and milling, relatively speaking.
If welding is occurring then that is an indication of high friction and heat. You're on the right path to increase your feed rate if you cannot decrease your spindle rpm. Also, large diameter mill bits will have a higher angular velocity than a much smaller bit for a given rpm.
37
CamBam help (General usage) / Re: Kerfs?
« on: November 08, 2022, 02:32:04 am »
I'm not quite sure what your wanting to achieve, but maybe this CamBam forum post of mine from 2016 may help regarding doing an acrylic-in-acrylic inlay. There are a lot of good input and suggestions from users on this CB forum as well.
https://cambamcnc.com/forum/index.php?topic=5841.msg46437/index.php#msg46437
Good luck, and be sure to read the entire threads and see all the images posted as the results keep getting better.
https://cambamcnc.com/forum/index.php?topic=5841.msg46437/index.php#msg46437
Good luck, and be sure to read the entire threads and see all the images posted as the results keep getting better.
38
CamBam help (General usage) / Re: JPG and rule of thumb?
« on: August 12, 2022, 01:07:48 am »
It seems like the image you found with a higher pixels would work just fine if used as a background image for CB, that would used to create a CB polyline trace file to be used for engraving or milling.
What am I missing?
What am I missing?
39
CamBam help (General usage) / Re: JPG and rule of thumb?
« on: August 11, 2022, 22:04:06 pm »
As a rule of thumb a jpg image should be 2 megapixels or higher if you are wanting to trace it out with CB. 300 x 150 pixels is miniscule and equates to 45,000 pixels.
40
Members Projects / Re: 'Got it done, even though the body is weak!
« on: August 02, 2022, 22:11:31 pm »
Great idea, or how about those motorized kick scooters?
41
Members Projects / Re: 'Got it done, even though the body is weak!
« on: August 02, 2022, 01:39:38 am »'Knocker,
I have a rolling transport cart that transfers one sheet from table-to-stack, or stack-to-table. But the pallets won't fit in the router shop door, so we have to park them outside the door, and carry them by hand - one at a time - with a sheet-lift-bar (similar to a drywall hand carrier), until we get them fully inside the router bay.
Once we get them on the cart... no problems. It's just getting them IN there that is the chore. The clearances demand that the path from pallet to the cart be uphill (slightly -- about 5") and about 12-15 feet from pallet to cart.
Lloyd
Oh, so there was a "we"?
42
Members Projects / Re: 'Got it done, even though the body is weak!
« on: August 01, 2022, 21:00:37 pm »Being 73 makes physical work harder. I had to move five 124 lb (56.25Kg) sheets of goods from a pallet in the barn 'main' bay into the storage rack in the router bay.
I got it done, with no death or serious injuries. But MAN, I would love not to have to move heavy stuff like that!
Maybe I need more time on the weight bench and muscle 'cycle. I haven't done but ONE of these in the last two years, and it was miserable. Done, but not happily!
Lloyd
We're the same age, and I can't imagine muscling that much weight unless it is on a low friction skid, without something on me "popping" or letting go. Nice going, Lloyd!
43
CamBam help (General usage) / Re: Can't get repeatable concentric pattern cut
« on: July 09, 2022, 18:51:19 pm »
It is an eye opener to see how costs for a small, basic CNC machine have grown the past 12 years.
I found this website of Patrick Hood-Daniel back in 2010 while exploring buying a CNC machine or building my own Do-It-Yourself CNC machine. Machines he sells range in sizes from mid-size to large but there is also a wealth of information in this website's Gallery from people who built their own machines.
https://buildyourcnc.com/creationsgallery.aspx
I was surprised to find (just now) that my DIY build contribution is still in his Gallery page, here:
https://buildyourcnc.com/AldenGCNCMachine.aspx
This was my first "build" using only a table saw, drill press, hand drill and other basic hand tools and wrenches. I think my total cost was close to $700. With it, I learned what it's construction could and could not withstand, but it was more than accurate enough to maintain an XY accuracy of .007" and a Z accuracy of .001". I only had a Dremel Tool for use as the "router" and it had manual speed control that worked amazingly well. Once I experienced the limitations of the Dremel Tool I started planning an upgrade to use a Porter Cable 890 Router.
Once I had used my first Dremel based CNC for cutting 1/8" to 3/4" plywood, 2" x 2" oak, plexiglass, brass and thin aluminum, I then used it to cut out the 3/4" MDO plywood parts, mill all the holes, slots, etc. to make a better, more rigid version, the one I still use today. Photos of my 2nd generation DIY CNC I believe are in posts on this forum.
Now maybe you are not in a position to undertake a DIY build, but I mention all this to encourage you to seeing what other people have accomplished and what sizes of stepper motors for axis control can and cannot do, based on their mechanical design.
Your small CNC is mind-blowingly compact, but it also has small torque stepper motors and good for only very light duty.
I found this website of Patrick Hood-Daniel back in 2010 while exploring buying a CNC machine or building my own Do-It-Yourself CNC machine. Machines he sells range in sizes from mid-size to large but there is also a wealth of information in this website's Gallery from people who built their own machines.
https://buildyourcnc.com/creationsgallery.aspx
I was surprised to find (just now) that my DIY build contribution is still in his Gallery page, here:
https://buildyourcnc.com/AldenGCNCMachine.aspx
This was my first "build" using only a table saw, drill press, hand drill and other basic hand tools and wrenches. I think my total cost was close to $700. With it, I learned what it's construction could and could not withstand, but it was more than accurate enough to maintain an XY accuracy of .007" and a Z accuracy of .001". I only had a Dremel Tool for use as the "router" and it had manual speed control that worked amazingly well. Once I experienced the limitations of the Dremel Tool I started planning an upgrade to use a Porter Cable 890 Router.
Once I had used my first Dremel based CNC for cutting 1/8" to 3/4" plywood, 2" x 2" oak, plexiglass, brass and thin aluminum, I then used it to cut out the 3/4" MDO plywood parts, mill all the holes, slots, etc. to make a better, more rigid version, the one I still use today. Photos of my 2nd generation DIY CNC I believe are in posts on this forum.
Now maybe you are not in a position to undertake a DIY build, but I mention all this to encourage you to seeing what other people have accomplished and what sizes of stepper motors for axis control can and cannot do, based on their mechanical design.
Your small CNC is mind-blowingly compact, but it also has small torque stepper motors and good for only very light duty.
44
Members Projects / Re: Not a project, but a personal request...
« on: July 06, 2022, 19:41:55 pm »
I'll say a long prayer for your son, Lloyd.
Could it be food poisoning?
Could it be food poisoning?
45
CamBam help (General usage) / Re: Can't get repeatable concentric pattern cut
« on: June 29, 2022, 18:51:47 pm »@airnocker - Don't know what precession is but, yes they were cut in sequence.
Thank you for your reply.
Gunter
Precession:
In your photos with the red arrows, if a line is drawn between the two opposing arrows of all the photos to represent the long axis of the eccentricity, the the line and its arrow end-points appear to be rotating the same amount about an off-axis center point between each successive photo. The rotation of the off-axis center point about the true center of the intended profile cut of the disc is precession.
As others have stated, this unintended movement of the disc's profile cut could indicate that one or more of your machine's axes has some freedom of movement issues.
Good luck with finding the cause. You could have a better forum than CB, with amazing experts on it to get help and suggestions for solving this problem.