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Topic: home made QFP50 dangerous proto board (Read 31236 times) previous topic - next topic

home made QFP50 dangerous proto board

I'm using the QFP50 dangerous proto board as a reference design to test the precision of a proxxon mf-70 retrofitted micro CNC.
I'm quite happy with the results!

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Re: home made QFP50 dangerous proto board

Reply #1
This looks cool! Did you do any kind of tests for shorts?

Re: home made QFP50 dangerous proto board

Reply #2
excellent job!

Re: home made QFP50 dangerous proto board

Reply #3
[quote author="tayken"]This looks cool! Did you do any kind of tests for shorts?[/quote]

Yep, all traces are good, manually tested them all.
If there's enough intrest I can post more info about the machine I'm using.

Re: home made QFP50 dangerous proto board

Reply #4
I'm interested, that looks really great!

Re: home made QFP50 dangerous proto board

Reply #5
It looks like the board is milled. It also looks like you could use bit faster spindle or slower feed rate, but it really looks perfect? What was this? 60 degree tip at 35kRPM moving 8mm/sec ?

Re: home made QFP50 dangerous proto board

Reply #6
A bit of info about the setup. I also did some pictures.
- The machine is a Proxxon MF-70 micro mill (http://proxxon.com/eng/html/27110.php), it costs around 300€ in Europe.
- DIY Bob card from pminmo (http://pminmo.com/PMinMOwiki/index.php5 ... sinterface) free!
- 3 x FL57STH56-3008B nema 23 steppers, got them from motion control UK, 27€ each (http://www.motioncontrolproducts.com/mo ... .php?cat=1)
- 3 x RepRap stepper drivers  v1, probably around 25€ each, got them 4 years ago so price may be outdated.
- Old PC power supply for the stepper drivers.
- Armadillo retrofit kit (http://www.ideegeniali.it/vendita/retro ... nutes.html) 135€
- EMC2 on linux ubuntu, in a old laptop. free!
- 10º V tip bits, at 20krpm (wich is the max for the spindle) and around 80mm per min for feed speed when etching, 10 mm per min when cuting the board (http://cgi.ebay.es/ws/eBayISAPI.dll?Vie ... K:MEWNX:IT), around 20€ 15 units.

Like Bogdan says, better quality can be achieved reducing the feed speed or increasing the spindle speed. It's a time-quality compromise.

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Re: home made QFP50 dangerous proto board

Reply #7
few hints. You can replace the old reprap half step modules (those are 297+298) that heat up like crazy and give only half step with new pololu drivers (cca 12$ each) that are used on new reprap boards and that heat waaaaay less + support microstepping (better precision - waaaay better precision)

10 degrees tip at 2kRPM .. wow, that looks too good to be true, with such pointy tip 2kRPM is hardly enough, that is super cool quality you are getting at such low speeds

Great post, thanks for it :)

Re: home made QFP50 dangerous proto board

Reply #8
Oh, Sorry, It's 20krpm!
I have corrected the post.
I bought one easydriver, wich I think is similar to the pololu, to do some tests.
Need to check first if they match the motors, and will not get smoked.
But now, as this project is finally working, I will go back first to get a extruder for my BfB reprap to work... (http://www.bitsfrombytes.com/forum/post ... cting-v201)
cheers

Re: home made QFP50 dangerous proto board

Reply #9
easydriver is more expensive, uses also alegro chip but only 750mA while pololu driver uses 2A driver (you can decide what current to drive motor with using pot on board). I think you do not need to force cool the easydriver but I doubt those nema23 will run at required torque with 750mA only

[quote author="fcobcn"]I will go back first to get a extruder for my BfB reprap to work... [/quote]

You are still getting that old machine to run :D .. too bad bfb was not more helpful with the documentation :(

I seriously suggest you do not get the bfb extruder as it is super expensive and not "Best out there". Since you have to make a mount bracket anyhow, I suggest you contact arcol.hu (if you are in europe) and get from him all you need to make extruder (wade drive print part, hobbed bolt, hot end) or if you are in USA then contact makergear.com and get from them whole extruder (they have some interesting solution also). bfb was cool but then they got purchased by that big usa company that messed all up, they are now super slow to respond to anything but "I will send you 10K$ give me 100g of filament" so you are way better off with arcol or makergear. Also, both extruders have better drive then bfb for the new materials as bfb's extruder have too long distance between pinch wheel and hot end mouth so you have less precision on the start/stop hence more ooze etc etc...

all best
Bogdan Kecman

Re: home made QFP50 dangerous proto board

Reply #10
After melting pounds of plastic, assembling and disassembling thousands of times the complete extruder, and being very frustrated, I came to the conclusion that the design was not even far to be ready for primetime.
What I may end up doing is using this CNC to build the mechanical parts, use the easydriver with a nema17, and get the arcol.hu hot end.
By the way, I also did some milling tests with aluminium, goes like butter.
thanks for the tips!

Re: home made QFP50 dangerous proto board

Reply #11
Al mills nice but depends a lot on what type of Al you have .. also you need to find a way to constantly add lubrication as it tends to stick to the bit ... using proper bits also helps :D

Re: home made QFP50 dangerous proto board

Reply #12
I'm using something like this for Al,
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It's a two blades front mill, used at high spindle speeds (>20krpm), low feed speeds.

Re: home made QFP50 dangerous proto board

Reply #13
I am using similar one had issues with "built edge" (when soft aluminum stuck to the tip of the cutting edge), I was told the only solution is to either add more cutting fluid or find different type of tip.... I finally gave up on milling completely .. toooo dirty, I have a lathe for some small work I need for reprap from time to time (making my own hot ends etc) but that's it

Re: home made QFP50 dangerous proto board

Reply #14
Did you tried by any chance to mill wooden reprap parts? It's another path wich I have not looked at.
Don't know even wich cutting tools to use with wood. Hints?