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Rascal CNC

nerdnic

nerdnic.com
Mentor
Hey guys,
Thanks for all the help!!! Inkscape worked great but there is a lot of stuff to take out. The laser cut dxf plans are also perfect for cnc cutting.

Does anyone know what feeds and speeds work for the stock 0.8mm endmills?
I'm cutting at 120ipm on the eBay .8 PCB upcut bits. My RPM is around 8k.
 
Was just going through the BoM for the Rascal and noticed that the stepper links are invalid, any advice on which steppers would work well or just any Nema 17 Nema 23 steppers?
 

Horseman3381

Well-known member
I ordered the parts for my own Rascal CNC a few months ago and finally got it assembled.

20191012_194203.jpg


I got my short kit from @TB RC and it was very well cut, sanded and painted. Any one thinking of building this I will vouch for their kits.

I also got the build video from @nerdnic and it was very helpful.

However, I am now at the point where I need to assemble the electronics. I think I have found several resources that tell me how to assemble everything, but if someone has build one that uses the electronics from the pats list and could take a few pictures of it and post it as a reference that would be very helpful and I would appreciate it very much. I can wire a house, and an airplane, but once you start introducing circuit boards, things are a little over my head.

Thanks
 
if there is any one still following this can you answer a few questions for me? is the rascal cnc kits still available, does anyone have a video either build, set up, or running it? the last post I see is dated oct 2017 and it is now 12-16-2019. this looks to be the right fit for me I was looking at the erc timesaver cutter but have no access to a 3d printer or know any one who does it. tried looking for a makers shop to see about having it printed but no luck. I will keep checking back here for a while and if I have no luck I will message nerdnick or sponz directly. hate to bother them with this as between their work and family they do a lot for us in the community as it is. I have been a follower of ft since they were keeping the mad swede locked in chads basement ( sorry david, tri copters fore ever!).
 

Fidget

Active member
@TB RC cut a kit for me last summer. Nerdnic can share the build video link with you.
I started building mine in September but didn't get it done the week I was off & haven't gotten back to it.
 

Horseman3381

Well-known member
if there is any one still following this can you answer a few questions for me? is the rascal cnc kits still available, does anyone have a video either build, set up, or running it? the last post I see is dated oct 2017 and it is now 12-16-2019. this looks to be the right fit for me I was looking at the erc timesaver cutter but have no access to a 3d printer or know any one who does it. tried looking for a makers shop to see about having it printed but no luck. I will keep checking back here for a while and if I have no luck I will message nerdnick or sponz directly. hate to bother them with this as between their work and family they do a lot for us in the community as it is. I have been a follower of ft since they were keeping the mad swede locked in chads basement ( sorry david, tri copters fore ever!).
I built a Rascle CNC this fall with a kit I purchased from @TB RC . As @Fidget said Nerdnic has a build video that is very helpful and gets you through the mechanical construction and wiring. However it stops short of assembling the electrical control components. If you decide to build one and need help with that let me know and I can get you come info on how to do it.

One thing I would mention is that the parts list links are a little out of date and it has the cheapest places to get the componets before shipping, but after considering shipping cost I ended up ordering alot of the more generic parts from amazon as I got them quicker, and shipping was alot less.
 
I built a Rascle CNC this fall with a kit I purchased from @TB RC . As @Fidget said Nerdnic has a build video that is very helpful and gets you through the mechanical construction and wiring. However it stops short of assembling the electrical control components. If you decide to build one and need help with that let me know and I can get you come info on how to do it.

One thing I would mention is that the parts list links are a little out of date and it has the cheapest places to get the componets before shipping, but after considering shipping cost I ended up ordering alot of the more generic parts from amazon as I got them quicker, and shipping was alot less.
thank you horseman 3381 I have been watching all the youtube and other post about the builds of different designs, finding and priceing parts is eye opening. banggood and amazon seem to have a lot of the material and there is another whose name i will have to look up and come back and post that carries what seems to be all you need to build but each place has a couple of items they don't seem to want to sell or are looking to pay off there or their children's college loans by selling them? don't get me wrong I worked in retail for decades and understand the facts of life you have to make a profit or your are out of business. (but then again if your no.#1 competitor can sell the same item or what looks like the same pc at 1/3 to 1/2 of what they are selling it at. come on get real) but them the ugly fact of shipping comes in to play instead of one or two orders well past the free freight level you now have four orders just below that level and what you might have saved is gone and your total cost is now higher than it has to be. Sorry about my ranting had to get it out of my system now to decide which one to build and put together my list and order the first lot of parts prob the electronics and stepper motors so I can amuse myself by doing a bench build and watching the little wheels spin back and forth yaaaaa, at my age it don't take much to amuse yourself ok now back to cutting out my dr1 or working on my piper pa25 crop duster balsa to foam board conversion from walt mooney plans from back in the sixties I kept his outlines and am blowing it up aprox 4x. once I get a set of drawings I like and build something that will build ok look ok and might actually fly I will sent in some photos and drawings so any one interested can try it so long thanks doug
 
The ER-8 spindle is cheaper, but much too high RPM. I didn't see a smaller spindle which had low RPM so I just ended up buying an ER-11 and speed controller last night. I did however spend a little more on a brushless spindle and controller in hopes it will last a little longer and be able to handle other materials a little better should I choose to play around with it more.
 
Does it make sense to get D-Shaft NEMA 23 steppers, so that the screw for the tooth pulleys can have a more flat surface area to bite into? Or will the cutout for the d-shaft cause issues with the pulley sitting correctly on the shaft?
 
Okay, more stepper questions.

I was doing some research and found out the DRV8825 drivers have a max continuous current of 1.5A per phase, and 2.2A with heatsinks and force air cooling for the drivers. I think the NEMA 23 steppers which were originally specified are a max 2.8A. I am wondering if I should either look at different drivers (not sure which one to use) or use a slightly less powerful stepper to improve the efficiency to and get potentially better holding power. Right now, I am leaning toward the latter since it appears to be only about an 8% difference in potential holding power, and potentially a lot less given stepper driver limitation.

This is the alternative stepper I have identified for the moment:
StepperOnline Nema 23 Bipolar 1.8deg 1.16Nm (164.3oz.in) 1.5A 5.4V 57x57x56mm 4 Wires

Any thoughts on this would be appreciated.

Thanks!
 
Something else I noticed related to the stepper amps is the suggested extension wire is stranded 22AWG. I am by no means an electrical engineer, but some of the charts I have looked at suggest .9A-1.0A is the max suggested power draw for 22AWG wire and 18AWG might be a better choice for this application. Again, I am not an electrical engineer... just doing some homework as I go through the parts list and am ordering stuff.

I found this on Amazon which looks like a good match:
https://www.amazon.com/dp/B0154LFKUO/?tag=lstir-20

I am probably just going to wait for the steppers to show up though. If they have 22AWG attached to them, it wouldn't make much sense to switch to 18AWG mid-run for extension wires.