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Discussion in 'CNC Mills/Routers' started by Hytech2k, Nov 28, 2014.
This is my journey on building a rack and pinion Ox variant called the F-117 CNC.
i was looking through the forum and ran into your build very nice work .
Thank you, much appreciated !!
It's been over a month since we installed the delrin wheels and so far so good. We have run this machine pretty hard and cut alot of signs so i'm pretty happy with their performance so far.. I will keep everyone updated if anything changes. Also check out my new build the "Triple Shot R-P-M" it's going to be a 6 watt laser cutter/engraver, a bowden 3D printer with a large heatbed, and a 400-600w CNC router as well. http://www.openbuilds.com/builds/triple-shot-r-p-m-area-51-cnc-parts.2307/
Here are a few more photos of some signs the F-117 recently cut.
We have a update as we have been researching what could be causing this reaction with the polycarbonate wheels. We have found that many lubrication's can cause this cracking problem in polycarbonate known as environmental stress cracking.
We were not aware of this until now and we have now learned that silicone will not cause this and is the best lubricate to use for polycarbonate . Spray silicone is what I use for my machine rails/wheels and so may be the reason we were not seeing this happen. The Part Store has been updated with this helpful notification / information.
This being said we want you to know that we are still forging ahead with ideas to be able use center V wheels on a stronger system without the added cost.
Thanks again for your patience as we work toward this common goal.
Some bearing oils can react with PC as well.
Correct Joe so its good that they are sealed. I think that in this case with the stress pushing the v apart combined with lubricants may have helped to cause these issues and using silicone as the lubricate seems to be the idea solution for any PC parts. If we have our way we will not need to think about this soon
The signs are looking great @Hytech2k glad to see your up and running again.
Oh that sounds suspiciously like a hint. Any clues for us on this side of the storefront?
Thanks Mark ! Sorry for the delayed response, we've been busy adding a 8 x 12' addition onto our office for the Triple Shot and additional storage. I've been running this machine pretty hard with the Delrin wheels and so far so good. I haven't noticed any real difference in cut quality. I'm looking forward to what you have in store.... Thanks again...
Wow sounds like a nice addition Gerald, very cool!
Thank you for the update on the delrin.
Very nice build. I am personally interested in copying the x-axis setup, maybe going to the steel v-rails (the use of epoxy to bond the rail is a good idea, I have a design using a HFS6-60120 extrusion for the gantry and custom steel v-wheels) over the delrin but only maybe. One reason to go to steel v-rail is the use of the steel v wheels from Inventables or others with sealed dual angular contact bearings. These are not the same as the steel v-wheels from Openbuilds, which don't over much over the delrin wheels since the bearings are still a "press" fit and hence there is slop in the wheel (most of delrin v-wheels from Openbuilds are more like a slip fit).
Gerald, any chance you are going to be making a production run of these kits? The biggest win for me is the R&P setup. Your website is still down....I'm basically re-engineering your designs now in Solidworks, though I'm going to stick with belts vs. the R&P setup for simplicity.
Also, curious why you say belts aren't good over the long term? I've had pretty good accuracy and repeatably from my GT3 belt setup. I have a GT2 15mm belt setup I am very eager to install, but it requires new plates all around.
Thank you for the compliment.
I will be putting the F-117 and the Triple Shot RPM machines for sale the beginning of the year, right now I have too many irons in the fire with my sign business to devote enough time to run the website and compile the kits properly. I am making some modifications to the F-117 based on my experience with it over the past 10 months, such as using 2020 rack and high torque steppers all around rather than the 1/4" 14.5 rack that's currently on the Y now. There will be a few other small changes but nothing major.
I am not against running belts at all, in fact I use a GT2 belt on my Triple Shot machine, just a narrow belt such as a 6mm GT2 or GT3 seem to have issues with stretching and play over time when used in CNC router applications. In my opinion it's not the best belt for this type of machine, a wider belt such as a 13-15mm would be much better,also more wrap on the stepper pinion would help as well. I cut at a fairly deep DOC and fast feed rates due to using this machine in my business every day, R&P is just what I prefer for reliability, accuracy, and strength.
what kind of programs are you running for you cad/cam thanks.
Tried sending an email but dunno if you check that account much. Anyways, I am considering getting some plates cut for the f-117. I have a stack of 5010 extrusion here are the house to build a large format machine. Due to its length I have decided to go open rail and rack and pinion. Could not find any other linear bearing system long enough. I originally intended to do screws on x and z but that would require a new plate design. I decided to bite the bullet and go with the f-117 since it's an established build that looks like it been working well..in a production environment no less. Couple of questions.
The files show 5010 version 7 on the side plates, version 3 on the gantry plates.
1. These are 5010 beams all around? (X and Y)
2. This version is for the 1/2x3/4 20 degree 20 pitch bolt on rack from Moore gear all around?
3. Is the bom current? I ordered a bunch of random openbuilds parts on the sale...most wheels, hardware, and open rail based roughly on the bom. Just want to make sure I have the right length screws and spacers.
4. Do u anticipate getting your store up and running to cut 6061 plates soon? I have a guy local that can cnc g10 with his Laguna machine, got another buddy working in a machine shop. Either of those guys might be able to help here in town, if not there are a few plate makers out there. However, your prices beforehand on your site were reasonable, I'd certainly consider it if you are back in the plate making business.
5. Ever consider belt reduction drives for this machine. I plan to and retrofit some onto the stock design after I have the machine cut.
I too am curious about the F117 build, @Hytech2k. Any chance that, if the BOM and drawings are not up-to-date, we can get a current copy applied to the site here?
This appears to be one of the more sturdy builds here and is done on a way that makes it easy to work on.
Of course, the problem with using the outdated files, is that you don't know where you are going to fail. If it's on the BOM, the failure is probably going to cost you money and time.
If it's on the drawings or plate drawings, that's going to be even more time... and for people like me, new window costs (ya know... for when I throw a piece of v-slot through the window in frustration).
Thank you for all the hard work and for posting it here so we can learn.
Love this build. Thanks for sharing!
What are you using for cooling the motors? My Nema 23's are running pretty hot and I'd be a lot more comfortable if they had some decent cooling from a heatsink, fan, or both.
Gecko 203V powering 570oz Nema 23s pulling 5A each. It's not painful to touch the motors but they're still running hotter than I'd like and I haven't found any heatsinks made for Nema 23's yet.
I wonder for a cnc using the 2 nema23 570oz on the Y axis, could it be quite better to go with a power supply of 70v instead of 48v ?
As more voltage will give an higher speed too... And the torque curve should not be affected by much. And just go with driver of 80v rating.
Speed isn't really an issue - it can already move faster than a 3hp router can cut so getting a good spindle will help more than trying to increase travel speed.
Or let say, at 70v , we can then used more effectively a 425oz then.. ? as to torque curve will expand of about more than 15percent..
Also, I've recheck so far data about the pignon gear, I understand as Pi x size will make a further movement...
But in real : What is the difference between a 15 , 16, 18 and 20 teeth ? Is the load will be higher with a higher teeth count or lower ?
Could this build and r&p setup be taken to a 1800 or 2000mm set up?
I'm running 1500x3000mm set up - the main rails need to be 5010 extrusion however so the holes for the wheels need to be moved 20mm up. I also recommend attaching the 5010 extrusion to side supports - personally I got 1/4" thick 4x4" aluminum angle from a metal shop in town in 2x 10' lengths.
A larger pinion will increase the load on the stepper, when I went from 14.5 to 20 pitch racks I used a larger pinion, the nema 23 I was using kept losing steps, changed over to a much high torque motor and the issue disappeared. Probably be better to use either gear or belt reduction to lessen the load on the stepper motor..
You could but you would have to deal with the v rail joints, you can buy rack as long as you need (up to 12ft I believe) but the v rail maxes out at 1500mm so you would have a slight "bump" possibly when the carriage passes over it.
I tried to go to your website, but something appears wrong when I do. Are you still manufacturing the plates?
Unfortunately not at this time, my sign shop experienced an unexpected surge in traffic and sales so I had to close the Area 51 site for the time being.
Oh, so the losing step could be again less, if go with a 16 or even 14 tooth.
In that case, as you said, probably a pinion running with belt could be the way. Is the 570oz nema will give any good in such setup... or they will just need to work at a lower amp ?
Like set the driver to max 3.7 - 4amp.. vs 5amp. As with the belt, it will turn less and compensate as to not have to swap the nema for a 400oz or so.. with less amp requirement.. if that make sense ?