One-Week Build

General discussion of laser machines

Re: One-Week Build

Postby bdring » Thu Mar 31, 2011 12:51 am

I applied a bit to each wheel after roughing up the inside and thoroughly cleaning the grease of the bearings. Are you sure the rails are parallel?
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Re: One-Week Build

Postby twehr » Thu Mar 31, 2011 1:01 am

LeonS wrote:
I have been having trouble with one of the delrin rings slipping off of its bearing. Should I apply a tiny bit of super glue?

- Leon


I'll let Bart give the official answer, but I can offer this. I have had them pop off as well. Every time, it was when I was applying some forces to the carriage (tightening belts, etc).

Remember from the instructions, Bart was very specific about which side the lip on the ring goes. I believe that was exactly for what I and possibly you have been experiencing. If too much pressure I's applied in the wrong way, they will pop off, as opposed to breaking.

Regardless, I have had no problem when not manhandling it.
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Re: One-Week Build

Postby bdring » Thu Mar 31, 2011 1:08 am

I think the instructions are different than my setup. I have the step towards the outside on the gantry ends. How did you mount yours Tim? In theory, one wheel should not be able to wander off on it's own if the rails are all parallel. It should stay centered on the rail. The gantry would have to move.
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Re: One-Week Build

Postby twehr » Thu Mar 31, 2011 1:28 am

bdring wrote:I think the instructions are different than my setup. I have the step towards the outside on the gantry ends. How did you mount yours Tim? In theory, one wheel should not be able to wander off on it's own if the rails are all parallel. It should stay centered on the rail. The gantry would have to move.


I went by the instructions...upper on gantry and front on laser carriage are lips on the plate side. All three adjustable rollers are the opposite, lips away from plate. The wording in the docs made it sound very specific that there was a difference. Note, fore me, the only ones that ever come off are the adjustable ones, and that seems to be protecting me from accidental breakage. As I said, it only happens when inappropriate forces are applied, which will not happen in use.
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Re: One-Week Build

Postby bdring » Thu Mar 31, 2011 1:40 am

OK, That is definitely not ideal.

I remember writing that before I actually installed one. I thought the the opposing steps would prevent walking off, but the puts the bearings out of line with each other. The wheels should all be facing the same way. Steps out on gantry. The wheels on the other side should prevent walk offs. I will fix the document.
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Re: One-Week Build

Postby twehr » Thu Mar 31, 2011 1:48 am

bdring wrote:OK, That is definitely not ideal.

I remember writing that before I actually installed one. I thought the the opposing steps would prevent walking off, but the puts the bearings out of line with each other. The wheels should all be facing the same way. Steps out on gantry. The wheels on the other side should prevent walk offs. I will fix the document.


When you say steps out on gantry, you mean the Y axis rollers? What about the X axis - is there a preference?

I will change all of mine in the morning when I reassemble everything.
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Re: One-Week Build

Postby bdring » Thu Mar 31, 2011 2:10 am

Y axis rollers steps are away from the brackets. On the lens carriage they also face away. The steps will fight gravity from pushing the wheels out on the carriage. I added section views to the drawings to clarify it.

See snapshots from drawings below. The new drawings are uploaded.

gantery_section.JPG

carriage_section.JPG
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Removing the V Rails

Postby twehr » Thu Mar 31, 2011 2:37 am

I disassembled the gantry in preparation for reassembly tomorrow with the new rail assembly. I took some pictures along the way that may be of interest.

[Photo - Gap in rail assembly]
rail gap.png


Now, before you start thinking, "Yikes, Tim, why didn't you see that when you put it together the first time!", remember that this is an extremely close camera shot. At normal viewing distance, with the naked eye, it is barely noticeable. Maybe we should be checking with a magnifying glass.

It was only the front (longer) rail on the x axis assembly that appeared to be off.

I decided I would try to remove the bad rail, just to see if I could.

[Video - removing the rail]


The video got cut off at the end (camera ran out of memory) about 10 seconds before I finished. I'll let everyone offer their opinion on how the final sentence should be completed.

[Photo - glue on rail and extrusion]
Glue on rails.png


I wanted to see how hard it would be to remove the dried super glue. First I tried Acetone - no effect. Then I tried Goof Off - again no effect. I even tried some super glue remover - guess it only works when the super glue is fresh. Finally, I tried a plain old razor scraper. Worked pretty well. The aluminum gave up the glue really easily. The steel took more work. In the next photo, you can see a small section of the rail that has been cleaned with the scraper.

[Photo - vrail and scraper]
Cleaned rail with scraper.png


I plan to go ahead and finish cleaning the rail and removing and cleaning the other rail, as well. May need them for another project later.
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Re: One-Week Build

Postby LeonS » Thu Mar 31, 2011 3:05 am

I also had the experience of the delrin rings slipping off if I put undo pressure on the bearings, just like Tim.

I have the lip away from the the carriage per Bart's diagram. Hopefully, it will be stable once everything is buttoned down and aligned.

- Leon
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Re: One-Week Build

Postby artwood_decor » Thu Mar 31, 2011 5:50 pm

I had a thought for some time about the Delrin wheels.
The idea would be to use 2 identical halves, both with shoulder for bearing, and attached with 3 screws M1.6.
I know from experience you can cut reliable thread in delrin.
The wheel diameter might need to be slightly increased.

Didn't pay too much attention to details, just wanted to share the idea.
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