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Joco’s cnc clone

Joco’s cnc clone

Postby joco » Sun Feb 01, 2015 8:06 am

I've been avidly reading the forums and looking at the buildyourcnc.com site (as well as many other DIY cnc sites/builds) working out the hardware, bearings, motion mechanics and electronics to get for a Blacktoe clone. Unfortunately the shipping costs of a whole kit to NZ is just more than my budget can bear. So I have compromised by designing based heavily off the Blacktoe's shape/ideas while purchasing as much as practical of the "vitamins" for the build from the lads at buildyourcnc.com.

Anyway, I thought I might share the journey as I go along starting with the design work. As a little background I'm an IT Project Manager/Consultant (20+ years in the game) so not really much of a mechanical back ground. I have built a "ReRap Prusa i2" 3d printer from scratch and then a "Cyclone 2 PCB Factory", so not completely useless just mostly. ;)
I'm also pretty comfortable with software so using a CAD tool for the design seemed logical. Anyway, using my aging 2009 MacBook Pro and FreeCad 0.15 (yes the bleeding edge version) I have set off on the road to CNC goodness with all the deadends and pot-holes that I am sure will be encountered along the way.

Here are some initial images as I work out all the parts of this beast before buying lots of wood and stuff. All ideas, suggestions, corrections etc would be very welcome.

WIP Designs:
assembly001.png

assembly002.png

assembly003.png

y-transport-assembly001.png

z-axis-assembly001.png
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Re: Joco’s cnc clone

Postby larry104 » Sun Feb 01, 2015 9:55 pm

Hi Joco,

I finished my Blacktoe clone a few months ago - how are you planing to cut these parts? By hand? I highly recommend building the book build first as it is ultra easy to build and fairly inexpensive - most parts like the electronics can be re-used on a bigger build. The big advantage is that you can use the book build to cut the parts for your bigger design with high precision - which is needed! Also you get tons priceless learning cycles ...

IMG_2062.JPG

IMG_2125.JPG
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Re: Joco’s cnc clone

Postby joco » Mon Feb 02, 2015 12:29 am

larry - nice looking build. Looks like you have used MDO or HDO plywood?

On the cutting front, the plan was to get the files to a local provider to cut them all out. $120NZD base setup and evaluation of plans then $2NZD per minute of cutting time. They can also source the right quality plywood for me at more competitive prices than I can get as a non commercial customer.

To help with the design I plan to do a scale model to access part fit and look. Probably in either cardboard or balsa wood.

I'm not anti doing the book build just not sure I want to do that build then go straight on to what I really want to make. Of course if I modify the book build to have aspects of the Blacktoe (e.g. chain drive system) I can get a lot of the hardware I will need (sized for the Blacktoe) but use on book build for learning. Either way I still need to do all the design work like I am at the moment. Which buys me time to consider all options. :)

Cheers.
joco
 
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Re: Joco’s cnc clone

Postby joco » Wed Feb 04, 2015 10:21 am

I have been using my time on the train to work and home to continue to evolve the parts. Here are some improved gantry side drawings with place holders for drive and idler sprockets as well as the angle rales and v-bearings to help position holes correctly.

LeftGantry001.png


Form the image below you can see there is opportunity to extend the bracing "wings"of the cross table spans down to just above the base of the idler sprockets and get a 3rd fastener in place. This would also provide a mount point for a cover over that whole chain/sprocket assembly to remove the chance of clothing or fingers getting caught up.

Just for the record I do know there is an error in the holes on the left side. Its in my defect log. :oops:
LeftGantry002.png
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Re: Joco’s cnc clone

Postby joco » Fri Feb 06, 2015 5:06 am

Did some more searching for wood supplies today and had a good conversation with the local Mitre10 Mega tradesales people. They have very clean looking construction grade 11 ply Okume faced 18mm plywood. Given its local and easy get with the trailer I think I will adjust all the plans for 18mm thickness plywood. Its just much more plentiful in local stocks than the 19mm stuff. Not looking forward to tweaking the plans by 1mm. So many little dimension changes.

After some further thinking and investigation a Book Build as suggested by Larry is looking more and more appealing. To give it a little extra rigidity I might use this 18mm ply as the material. I gives me practice working with that material as well as some of the benefits of the rigid properties of plywood. Plus I just like plywood versus the super cardboard we call MDF.
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Re: Joco’s cnc clone

Postby larry104 » Fri Feb 06, 2015 4:32 pm

If you want to build the BB I suggest reading Phill's thread http://www.buildyourtools.com/forums/index.php?f=8&t=2072&rb_v=viewtopic - he came up with a few great ideas to make the BB more rigid.
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Re: Joco’s cnc clone

Postby joco » Sun Feb 08, 2015 8:06 am

Thanks Larry. Phill's thread is a very good read. Not least of which is seeing the signs he is able to turn using his machine.

Just working out the BOM as well as figuring out what I will do "by the book" versus what I want to change. It will be much simpler than the Blacktoe clone as you have noted.
joco
 
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Re: Joco’s cnc clone

Postby larry104 » Sun Feb 08, 2015 5:02 pm

The changes I did were:
    Added Phill's tension idea of the BRA's.
    Added table saw cuts to be able to position the BRA's more precisely.
    Added different motor mounts to be able to get to the set screw of the coupler.
    Welded the lead nuts onto a strip of metal for better alignment.
    Added a different router mount.
IMG_2911.JPG

IMG_2912.JPG

IMG_2913.JPG
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Re: Joco’s cnc clone

Postby larry104 » Sun Feb 08, 2015 5:24 pm

One more thing - You need 3 stepper for the BB - if you go with a single X-Axis motor on your next build the motor is not powerful enough. I just bought a 4th motor/driver and use 2 X-Axis motors on my new build - something to consider.
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Re: Joco’s cnc clone

Postby joco » Mon Feb 09, 2015 12:42 am

Larry - thanks for sharing, these are great! Any other insights that pop to mind please throw them out there.

On the stepper front I had been planning on using 3 x NEMA 24 425 oz-in motors. Are these larger than what you used or the same size? I believe they are the spec used on the Blacktoe kits so in "theory" should be enough to push things about. Or did you end up using a NEMA 34 651 oz-in to move the gantry along the length of the table?
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