cnc machine z-axis and other things
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Derek Eggers
Sep 13, 2012, 10:50:23 AM9/13/12
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Dave,
--
Derek Eggers
How did your CNC session go?
I changed tools while cutting a part. Seems like a definite opportunity to introduce error, but it wasn't too difficult. I had some trouble with the z-axis. It's making that knocking noise again. I'd like to secure the lead screw so we don't have that. ...I could tear into it, but would appreciate advice if anyone has thoughts about it. Seems like we discussed adding some kind of lead screw bearing like the one in the link below. Do we have parts like this around or will we need to order it? I'd also like to thing about cutting new parts that were from MDF and broke, or possibly saturating them with PES (Penetrating Epoxy Sealer) to harden them.
It also seems like we have some un-parallel-ness between the table and the gantry, most noticeable in the x-axis. Wasn't a big deal when I was cutting profiles, but yesterday I tried a facing operation and an engraving operation. Both were less than pretty. I have an idea for a small leveling jig for the part I want to create. Basically a board with 3 or 4 t-nuts on the bottom and bolts that run through it to adjust the parallel to x-y axis parts. Then I'd mount my stock on top of this jig. Or I could even just shim it for simplicity. I also want to add top side wooden dowel pins to my jig so I can make multiple parts in the same g-code.
On other topics, dust is really building up. I apologize as I know much of it is my own. I hope to get further along on the brush-skirt soon. Also if we had more vac-pipe, or maybe thin-walled PVC I'd like to make a manifold under the CNC table so we could run small hand-held flex tubes and clean up around the machine as needed. ....later maybe we can make a vacuum clamp table. ....ok, too many "next steps" for now.
Lead Screw Bearing Link.
Derek Eggers
David Hempy
Sep 16, 2012, 1:04:16 AM9/16/12
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Good report, Derek.
I made good progress! Actually cut some good parts. My model needs a little refinement, but the cutting was spot-on to what I asked for. FWIW, I'm trying to build something like this: http://www.bedbathandbeyond.com/product.asp?SKU=15945966 The boys have one and love it. They cost over $17 new, so I figure I can afford to spend 30 or 40 hours to make my own. ;-) I ran out of time before finishing it. Have gotten myself derailed by building it again in Alibre. My first model was in Rhino. Change is hard.
That clunking sound means the Z axis hit the upper limit, and pulled the lead screw out of the coupling. The Lead screw now hits at the bottom end. The immediate fix for you is to simply drive the Z axis into the table, forcing the leadscrew back into the coupling. You'll only cringe the first time. The real fix is that we need to install limit switches, so it cannot crash at the top. Maybe tightening the collars and such would reduce the problem, but ultimately something has to give...might as well be the coupler. We also need a pair of y-axis limits, so we can auto-square and home the gantry.
We also need to replace the safety wire lashings I installed on the Z axis motor mount...to see us through the day for the Loudon Tech Art Show. I'm amazed it is holding up as well as it is. Four threaded rods, some nuts and a little creativity should do the trick. There is a section of threaded rod down there...near the Maker Bot.
Do you mean one end of the gantry is higher than the other? That would be surprising to me. I hope that's not what you're seeing. Anyway, any irregularities there will be eliminated when we surface the table...after we fasten the spoilboard down...after we paint the frame...after we remove all the machinery from the table... ::rolleyes:: I don't think a leveling device like you describe is going to be a real fruitful path...but knock yourself out!
If you mean the router is tilted off-axis, that's not so bad to fix. We've never trammed it, so it may well be off. I bought a big bottom-cleaning bit to surface the table...that should reveal a tramming problem quickly.
I looked at the brush situation the other night, and nothing genius came to mind. I did imagine bolting the four brushes in a rectangle, and just let it float around on the table, not connected to the head, but encircling it and getting pushed around all day. Might work...
In the "Cheap and Easy" department, I dragged a cardboard box under the table over, so the flap shields the PC.
I've got a 2" (?) hose off a vacuum queued up to bring in. It might fit the litlte shop vac someone left there. Good for cleanup, I hope. Also, there is a second port on the dust collector available.
We should probably have another few work days to revisit our dwindling to-do list.
-dave
I made good progress! Actually cut some good parts. My model needs a little refinement, but the cutting was spot-on to what I asked for. FWIW, I'm trying to build something like this: http://www.bedbathandbeyond.com/product.asp?SKU=15945966 The boys have one and love it. They cost over $17 new, so I figure I can afford to spend 30 or 40 hours to make my own. ;-) I ran out of time before finishing it. Have gotten myself derailed by building it again in Alibre. My first model was in Rhino. Change is hard.
That clunking sound means the Z axis hit the upper limit, and pulled the lead screw out of the coupling. The Lead screw now hits at the bottom end. The immediate fix for you is to simply drive the Z axis into the table, forcing the leadscrew back into the coupling. You'll only cringe the first time. The real fix is that we need to install limit switches, so it cannot crash at the top. Maybe tightening the collars and such would reduce the problem, but ultimately something has to give...might as well be the coupler. We also need a pair of y-axis limits, so we can auto-square and home the gantry.
We also need to replace the safety wire lashings I installed on the Z axis motor mount...to see us through the day for the Loudon Tech Art Show. I'm amazed it is holding up as well as it is. Four threaded rods, some nuts and a little creativity should do the trick. There is a section of threaded rod down there...near the Maker Bot.
Do you mean one end of the gantry is higher than the other? That would be surprising to me. I hope that's not what you're seeing. Anyway, any irregularities there will be eliminated when we surface the table...after we fasten the spoilboard down...after we paint the frame...after we remove all the machinery from the table... ::rolleyes:: I don't think a leveling device like you describe is going to be a real fruitful path...but knock yourself out!
If you mean the router is tilted off-axis, that's not so bad to fix. We've never trammed it, so it may well be off. I bought a big bottom-cleaning bit to surface the table...that should reveal a tramming problem quickly.
I looked at the brush situation the other night, and nothing genius came to mind. I did imagine bolting the four brushes in a rectangle, and just let it float around on the table, not connected to the head, but encircling it and getting pushed around all day. Might work...
In the "Cheap and Easy" department, I dragged a cardboard box under the table over, so the flap shields the PC.
I've got a 2" (?) hose off a vacuum queued up to bring in. It might fit the litlte shop vac someone left there. Good for cleanup, I hope. Also, there is a second port on the dust collector available.
We should probably have another few work days to revisit our dwindling to-do list.
-dave
----
Derek Eggers
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Derek Eggers
Sep 16, 2012, 6:10:25 AM9/16/12
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Dave,thanks for the feedback.
Cool part Dave. Your boys will love it. The economics of $17 for 30-40 hours of fun sound pretty good. We had similar results the other day and it was a blast. I think six of us got to work for about 3-4 hours on Niks cat food bowl holder. I'm not sure exactly what the typical cost is for a standard cat food bowl holder, but let's say maybe $10. We got at least 18 man hours of fun for a $10 part. I kind of feel like we are cheating the system or something.
Derek Eggers,
Derek Eggers,
Christopher Harn
Sep 16, 2012, 8:43:25 AM9/16/12
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I was reading the news and China has taken notice of your manufacturing
efforts and they are preparing to significantly ramp up production.
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