Machsupport Forum
General CNC Chat => Show"N"Tell ( What you have made with your CNC machine.) => Topic started by: Tweakie.CNC on February 26, 2009, 10:13:01 AM
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As a winter project i have slowly been building a 4th Axis. I did seriously think about making a scroll chuck but decided on buying a Sherline 3 jaw for the project. All the other parts (excluding the flex coupling) have been made from stock, some parts CNC'd others made on a lathe or mill.
There is still a lot of work to do but I thought I could post some pictures of the progress so far.
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Pretty dogone nifty there Tweakie !
Is there any way to adjust/remove any backlash ?
Again....COOL,
RC
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I hope you documented your design for the rest of us ;-) I think a 4th axis is my next project after my Miser and maybe concurrently with CNCing my watch lathe.
Vince
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Hi RC,
This is difficult to describe but as the 4 main parts of the case are not directly fixed to each other (they are keyed vertically) the small end plates can be moved vertically (and shims inserted) to increase the mesh of the gears to eliminate any backlash. The front and back plates are then clamped together by the 4 screws, trapping the end plates in position. The top and base plates trap the shims and make the whole assembly rigid. The stepper position will also be adjustable.
I am certain that initially there will be some degree of wear between the gears as they 'bed-in' so adjustment for backlash is essential.
Tweakie.
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Hi Vince,
I took a few photo's during making some of the parts and I will try to document the construction of the project on my website.
Tweakie.
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Looks great, I look forward to seeing someone actually use their 4th axis.... ;D
Dave
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Very nice Tweakie. :) Looking forward to seeing it in action.
Brett
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Hi Vince,
I took a few photo's during making some of the parts and I will try to document the construction of the project on my website.
Tweakie.
What is your website address?
Vince
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Vince,
Click on this little guy.
RC
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Thanks Tweakie, I like you approach to the backlash adjustment.
RC
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I'll never regret setting up this section. Your work is inspirational.
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Thanks Guys.
I will post more pictures as the project progresses.
Tweakie.
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What is the method of working out the diameter of the gear so thats you can cut the teeth to fit around exactly?
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Try this :-
Graham
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By mounting the blank on a bearing so it can freewheel and cutting with a tap as Tweakie has done, I would think all you need to do is make the circumference at the PD an even increment of the taps pitch..then add the depth of the thread to the PD to get the OD.
RC
Just rambling while waiting for ya Tweakie.....thanks
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Hi Folks,
My approach to cutting the gear wheel was nowhere near as technical as it should have been. I already had a 60 tooth spur gear so I knew in advance the diameter the finished gear was to be cut to. I machined 60 slots around the circumference of the blank (for the tap to engage) and went for it like it was a knurling operation on a lathe. The initial problem is that the number of teeth versus the circumference did not match because I did not machine the blank to the finished shape )=( it was initially too large in diameter at the point where the tap first touches (difficult to explain but I hope you understand). So there was some argument between the tap and the blank but this subsided to harmony when the diameter and pitch became correct.
As with all things, if I was doing it again I would probably do it a different way but the way it was done worked. I have since seen examples of this type of gear which has been cut radially into two discs which are spring loaded against each other as a way of eliminating backlash.
Tweakie.
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Just finished making the stepper motor mounting this morning - can't wait to try it out but I have to do a bit more electronics to extend my driver card to include a fourth axis driver.
Fortunately, I have a stepper test rig so I can run it on the bench just to make sure there are no tight spots and that the stepper has enough torque.
Here are a couple more pictures.
Tweakie.
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Looking GOOD Tweakie !
You're THERE man.
Making chips soon....or dust.....probably both.
Thanks,
RC
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I haven't the faintest idea how to set up Mach to drive a fourth axis yet. There are plenty of posts on this subject (i've checked already) so I will have to do a lot of reading before I can make anything.
Tweakie.
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Looks like a great unit there, tweakie :)
Dave
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Great job on the fourth axis Tweakie.
Love how you have built in alignment to the base.
Very interested to see how the gear adjustment goes in use.
Well done, Greg
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Well that's it - the mechanicals are all complete now, it just leaves the electricals to be sorted.
Tweakie.
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A true work of art in itself Tweakie. I'd hate to see you get it dirty LOL.
Looks real nice !
RC
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Tweakie,
Man, you sure do goood work!
Thanks for posting , Glenn