Ynnek - I found that thread about helical rack and pinion info. I posted a reply in my thread but it'll probably be more useful to you in your own thread
http://www.cnczone.com/forums/genera...ck-pinion.html
Ynnek - I found that thread about helical rack and pinion info. I posted a reply in my thread but it'll probably be more useful to you in your own thread
http://www.cnczone.com/forums/genera...ck-pinion.html
So I am re-thinking some design. Steel being cheaper than aluminum, I am considering either 3/4 or 1 inch steel side plates instead of 6061 aluminum, along with using a rectangle steel tube, 3" x 6" which would be $100 - $120 less than extrusion. Downside would be costs of extra machining. I will probably build the Z axis all steel also, much cheaper than aluminum.
the all steel gantry with everything attached would be around the 200 mark
Two of the motors I have are 580oz/in & ftwo are 690oz/in, I would have a 3.2 belt reduction.
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Along the lines of my previous post, I have to determine if my motors would be up to the task on such a heavy gantry, if not, then my costs would then increase, then the savings from the materials change would be non existent.
Back to semi-original plans. I can get the 8020 beam cheaper than EBAY, with no shipping charges either, local pickup, as my brother lives near where they do their shipping in Indiana. I will be heading that way some time this summer. I still may go with building the Y uprights & bearing trucks along with the complete Z axis, from steel.Not as heavy duty as all seell, but I feel it is a good compromise.
You might want to consider designing your Y uprights using 8020 if you're going there anyway. The extra cost would be negligible I would think especially if you're going to pick up locally. And their cuts are precise enough that you would get two, equal length uprights which would make leveling/squaring your gantry easy.
Only the gantry beam, X, will be extrusion. The Y uprights will be either 3/4 or 1" steel. Cheaper than aluminum & I can get them CNC machined where I work.
The design can be viewed here, A360
Question here, looking for advice. Within my design, I am using SBR25 supported round rail for bot X & y and SBR20 supported round rail on my Z, as I got it free. I do not have enough rail for both X & Y. I will have to buy some. I was thinking of buying some 20mm profile rail from Automation Overstock. There will not be that much costs difference between that purchasing SBR25 with bearings on EBAY coming from China. Any downside to using two different types of linear guides in a build or, should the be kept uniform? At the end of the day it just has to function properly.
I don't see any downside.
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After looking at the overall costs, I will go with the profile rails on the Y axis. Down the road I can upgrade the rest of the machine to the same. Get the machine up and running, get some paying jobs & let it pay for the upgrade itself. Any good or bad reviews of the BLH linear guides at Automation Overstock?
None that I'm aware of. If it helps, I bought all my linear bearings and pinion rack from from Kent at Automation overstock. He was very helpful and I would buy there again.
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Thanks for the input Jumper. THough I have a thread going, I have not actually started the build, short of acquiring stuff. Working 65 hours a week does not leave a lot of free time. I will though get started on laying out the electrical, wiring & bench testing. I have a cheap BOB to use in the interim. I have a CNC4PC C32 bob I need to get checked out. If that is not a viable option I will probably go with the UC300ETH & the MB2 I am currently laying out the changes to the linear rail, in Fusion360. Also, I intended to buy helical R&P, i will use the straight R&P I currently have. Also designing a dual pinion R&P drive to help compensate for backlash. I will either settle on building these or buying from CNCRP.
Here is my dual pinion design attached to my X axis truck.
A360
How big are those pinions?
What most people use, is a 3:1 reduction, with a 1" pinion, which gives about 1" of travel per revolution of the stepper.
CNC Room will soon be selling the UB1 board, made specifically for the UC300ETH.If that is not a viable option I will probably go with the UC300ETH & the MB2
UB1 Breakout Board [UB1] - $180.00 : CNCRoom, The Room for CNC'ers, from Mini to Big machine, from Hobbyists to Gurus - ????????????????? ???????????????????????????????
Gerry
UCCNC 2017 Screenset
http://www.thecncwoodworker.com/2017.html
Mach3 2010 Screenset
http://www.thecncwoodworker.com/2010.html
JointCAM - CNC Dovetails & Box Joints
http://www.g-forcecnc.com/jointcam.html
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
I like your dual pinion design. Are they tensioned against each other or just driven by the single belt? FWIW, I never found backlash to be a problem even on my first machine which was pretty unrefined. And I only had a single rack and pinion drive. I can't remember if I ever measured it but if I did it must have been unremarkable. Anyway, a dual rack and pinion drive like yours is a better design in several respects and is pretty rare on a DIY machine.
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Single belt, wrapped around idlers to tension them against one another. Here is a screenshot
A360
Well, I will purchase my steel tomorrow & possibly the linear rail I need also. Things are moving forward, albeit slow.
Wondered if you ever found out any more about the BLH stuff from Automation Overstock? Thinking of my own 1st build and it sure looks interesting...
Well. After putting things off because of work and a possible out of state move, I am back on my project. With a slight change though, I never did order the steel, as home projects took priority. Plus I have spent the majority of my time on the road this year, travelling for work. While at my local plant the other day, I stumbled upon an old machine frame that has been tagged to be cut up & sold for scrap. There is a good chance I will get it. It is a bit overkill, but would be free. Built from 5" square, 1/4" wall steel tubing. The dimensions are as follows, 62" x 82" x 24" tall. Plenty big for a 4 x 4 machine. With the savings from not buying materials to build a frame with, I will probably purchase some 25mm profile rail from Automation Overstock, along with the helical R&P. Should be a much better machine. Included is a photo of the frame I described.
Question if anyone wants to chine in. The frame is 82 x 62. Plenty for 48" of travel on both x (gantry) & y. Advantages & disadvantages of making the gantry (x) on the long side of the rectangle?