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It's been a lengthy hiatus but I'm again moving forward with my 8020 build. Today I sized some 1/2" aluminum plate for the Z assembly backing plate. I also cut to length the two 8020 pieces that will receive the THK linear rails and allows the THK ballscrew to nestle between. The pics show the pieces mentioned in mockup. A bit of drilling and tapping is next up. Stepper mount plate to follow...
Senna
It has been a long time since your last update.. Congrats on getting the proverbial ball screw rolling.Originally Posted by Senna
Your Z axis, I just read through a post yesterday of someone making one very similar to yours and loved it. I'm thinking about taking the same route on my next cnc build. Looks great and is a very doable design.
Looking forward to more updates.
Lacking metal working machines has left me with reliance on my woodworking equipment. I was very reluctant to attempt to machine 1/2" aluminum plate on my Powermatic table saw... but I've procrastinated too long on so many details on this build... it's time to make that faith leap. Reading a bit about the subject of cutting aluminum gave me sufficient confidence that if approached in a sane manner and using carbide tooling... I would be successful. Turns out that it cuts quite well when done properly. I had absolutely no issues other than the caveat of eye protection and I did employ long sleeves shortly after beginning to cut. The chips got fairly hot and I sought protection.
It's certainly not a quick process with the need for multiple shallow depth cuts... but I accomplished the required plate sizing easily. Now I'm stalled waiting on a UPS delivery of needed hardware...
Senna
The UPS truck came yesterday with the required hardware... so I pushed on with the Z assembly construction. Today I reached the point where I have the entire Z axis completely thought out with all the warts massaged into compliance or eliminated. I have it about 90% completed with just the Z plate and router mount left to assemble. Oh... I also need to fab a ballscrew attachment bracket.
Designing a machine on a conceptual level and subsequent construction from such plans is fraught with the potential for mistakes. I spend copious amounts of time staring at my machine construction and cogitate... attempting to see the operation and potential problems. So far... things have gone quite well.
I'm getting close to the point where I will need to start on the electronics... a subject I'm woefully lacking in knowledge... sigh...
Senna
Spent these last few days finishing off the base design and build. It was pretty much complete but I finally got around to figuring out the stub leg attachment without having to purchase more bracket hardware from 8020 Garage. The legs came out exceptionally sturdy. I made the attachment brackets out of 1/2" plate. I also installed the leadscrew assembly... once again using Ahren's (www.cncrouterparts.com) bearing blocks, Dumpster's (www.dumpstercnc.com) AB nuts, clamps and couplings. The stepper is a 305 oz HobbyCNC 23-305-DS8A.
I just about had the gantry finished off and managed to strip two of the Y axis linear rail attachment nuts. DOH! The amount of hardware needing removal to get the rail off was disheartening! Talk about two steps forward and three steps back...! My shop made T-nuts were tapped aluminum. Not the correct material for this application. I now need to rethink the hardware to insure it doesn't happen again.
Here's some progress pics...
Senna
The decision to drill and tap the stepper mounting lugs was made when I determined that two of the stepper mounting holes get covered by the 8020 extrusion making the use of a machine screw and nut a bit problematic. The choices were a stud protruding from the mounting plate, a tapped mounting plate, or the choice I made... countersunk through bolt and tapped mounting lugs on the stepper. The stepper gets bolted to the plate and the plate then gets screwed to the 8020 machine frame. A slight enlargement of the plate to machine mounting holes allow for shaft alignment. If this arrangement doesn't work out and proves to be an issue once the machine is in operation... I'll remake the stepper mount plates WITH my machine and go with a tapped mount plate.
The AnTek power supply arrived this morning! My three G251 Geckodrivers and a Siemens E-Stop I won on eBay also showed up. I'm very close to where the mechanical build is finished and the electronic assemblage begins. The one issue I'm pondering is the BOB. In hindsight I should of purchased a G540 and much of what I will now fuss about would be a no brainer. My current investigations are the PMDX 122 and the CNC4PC C11G... of course having no clue as to what all the specs mean isn't making things any clearer...
Senna
I'm scouring the threads for schematics of controller assemblies... hoping to gleen information that might further my understanding and subsequent build. My background had a strong mechanical grounding but completely lacked an exposure to even the simplest electronics. The language and terms used so casually by many on this board in discussion of controller electronics is often completely foreign and I've been mostly frustrated to date.
Carrying on... my machine is very close to completion. A few critical dimensions are lacking of the particular router I've selected (the M12VC Hitachi) but yet purchased. The Z axis plate will be sized based on these dimensions... so it awaits fabrication.
I did mate the base assembly with the gantry. Both have been squared & trued up with relation to each other. I will be assembling the Y-axis on the machine in the next couple days... then the wiring commences.
Senna
I know this thread is getting close to the 1 year mark, is that inspiring you any to finish? You certainly are close now.
Well... time has a way of getting away from you... OR me in this case. It's not inspiration so much... more a challenge of finding the funds needed to push the project forward. The financial meltdown didn't do me any favors with regards to fiscal issues. Money problems aside... I am feelin' it! So...so close!!!
I'll be putting the Y carriage together today... which pretty much finishes off the mechanicals. I need to make a specialized tool to help in assembling it in situ. I'm also hoping to get some 'guru' help with the wiring of the controller. Electronics... not my strong subject...
Senna
Inexpensive T-nut substitute>
http://www.mcmaster.com/#weld-nuts/=3h0a2c
Patience and perseverance have a magical effect before which difficulties disappear and obstacles vanish.
Senna,
If you need help with the wiring, I would be happy to give you assistance.
Jeff...
Patience and perseverance have a magical effect before which difficulties disappear and obstacles vanish.
Jeff... that's terrific...thanks!!! I have a schematic that I've drawn that I'll attach as a jpeg but also as a PDF. The PDF can be zoomed without the jaggies you get in a jpeg. I'm a total noob when it comes to electronics so I'm expecting numerous errors. I'm working with an AnTek 50Vdc power supply, Gecko G251 drivers, a CNC4PC C10 breakout board, and HobbyCNC 23-305-DS8A steppers.
As an example of how lost I am... I think from the schematic HobbyCNC sent along with the steppers... you connect the designated 'A' and COM wires, the 'a' and COM wires, the 'b' and COM wires, and the 'B' and COM wires together making an 8 wire stepper into a 4 wire stepper...??? which makes it a unipolar 305 oz-in stepper??? I'm clueless here... hence the need for assistance...
Today was mainly about the Y axis AB nut bracket and alignment. I fabbed the bracket and the needed spacer... lots of drilling and tapping. Worked out nicely.
I'm going to Loctite (Blue 242) numerous machine screws as I assemble the Y carriage so a trip to town for a tube is in order. No assembly today...
Senna
Last edited by Senna; 09-03-2009 at 10:26 PM. Reason: spelling...
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