Angle bracket/Y axis travel

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Angle bracket/Y axis travel

Postby cpdude » Thu Apr 21, 2011 4:35 am

Has anyone else besides me and j_siegel moved the angle bracket to the top of left Y axis extrusion? What am I talking about? Well here's a picture of j_siegel's laser (Trogdor the burner):
Complete1.jpg

Note that the angle bracket is on top of the the left Y axis extrusion.

Now take a look at Bill's laser
Image
Note that the angle bracket is on the bottom of the left Y axis extrusion.

Why would you move the angle bracket to the top? We'll on my laser the Y axis travel is limited when the left gantry end bracket hits the left Y axis idler. I found that with the angle bracket on top the left Y axis extrusion the left Y axis idler can be move about an inch further toward the front of the laser. This increases the Y axis travel on my laser by about an inch.

Does this work for anyone else or is my laser special?

Brian
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Re: Angle bracket/Y axis travel

Postby tylerv » Thu Apr 21, 2011 5:50 am

I haven't gotten the motors or pulleys installed yet, but I moved the bracket as you did a couple weeks ago when installing the HDPE idler part. I don't remember now, but I think the drawings show this particular angle bracket on the top of the extrusion.
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Re: Angle bracket/Y axis travel

Postby LeonS » Thu Apr 21, 2011 11:36 am

I put my angle bracket above the left Y rail for the same reason stated above by Cpdude. I went through the same logic and sequence of events that he did. After making this "improvement" I noticed that the system assembly drawing shows the bracket mounted on top of the Y rail. Oh well. Some of the subtleties might be best stated explicitly in the instructions.

Bart's hope to let the assembly drawings be the prime documentation for assembling the laser makes a lot of sense. If we could interactively rotate, pan, zoom and "fly around" the model to answer questions like the subject of this thread, it would be really cool. Thingiverse has a plugin that allows you to interactively manipulate a 3D model and explore it within a browser. It would be awesome if we could do that with the 2.x assembly drawings.

The fact that Bill's laser didn't have this angle bracket located above the Y rail explains why Bill was having problems getting a full 12" of Y travel. I hope he has remedied that situation.

Cheers,
Leon
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Re: Angle bracket/Y axis travel

Postby LeonS » Thu Apr 21, 2011 12:02 pm

Actually, it was twehr that was having the trouble with the Y movement. Did you get that working properly Tim?

- Leon
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Re: Angle bracket/Y axis travel

Postby bdring » Thu Apr 21, 2011 12:22 pm

The bracket was placed above and below to improve resistance of the extrusion to twist. This was done back in the virtual CAD world. In general I try to avoid placing all fasteners on the same axis. In reality, there probably is no real twist force to worry about and it is strong enough either way. Something else would probably fail first. Also the middle horizontal extrusion will help prevent twist.

Does moving it below cause an interference with the front pulley?

I would be happy to change the drawing to whatever everyone thinks is the best location.
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Re: Angle bracket/Y axis travel

Postby twehr » Thu Apr 21, 2011 12:57 pm

I mentioned the issue of running into the bracket in this post - http://www.buildlog.net/forum/viewtopic.php?f=4&t=406&start=20#p2787 I also said I would post pics and seems I may have forgotten to do that.

Looking back at the photos I took, I know why - a couple were very out of focus and I never got around to retaking them. But I will post them anyway for anyone that cares to see them - you'll get the idea.

First - why I did NOT move the bracket to the top. When I discovered the movement limitation, I was going to move it, but realized that doing so would make it impossible for me to drop the front v wheel off the v rail if I ever had to remove/reinstall the gantry. So I opted for this solution.

I modified the idler bracket to allow it to mate up with the angle bracket - giving me about 7/8" more room.

[photo 1 - old and new idler bracket form]
photo(2).JPG


[photo 2 - old and new idler bracket form - better angle]
photo(3).JPG


[photo 3 - placement with original idler bracket]
photo(4).JPG


[photo 4 - placement with modified idler bracket]
photo(5).JPG


The modified idler bracket has since been straightened up a bit and mates nicely with the corner brace. I just don't have a photo of it.

I cut the wedge out with a hacksaw - really easy to do. Note that I also moved the keeper screw to allow max removal of the material.

I don't necessarily recommend this method to everyone, but if you feel like getting a little extra gantry movement, it does work very well.
Last edited by twehr on Thu Apr 21, 2011 4:17 pm, edited 1 time in total.
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Re: Angle bracket/Y axis travel

Postby twehr » Thu Apr 21, 2011 1:00 pm

bdring wrote:The bracket was placed above and below to improve resistance of the extrusion to twist.


Gee - I thought it was supposed to be both below. Maybe I misread the drawings. But being above does interfere, I think, with the front roller on the vrail - see my other post.
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Re: Angle bracket/Y axis travel

Postby cpdude » Thu Apr 21, 2011 3:51 pm

twehr wrote:...But being above does interfere, I think, with the front roller on the vrail - see my other post.


Tim, I'm not sure that I'm reading this correctly. Are you saying that having the angle bracket above the extrusion causes interference with the left gantry end bracket? :?

Also, the link provided two posts up doesn't seem to work for me. ;)

Thanks!
Brian
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Re: Angle bracket/Y axis travel

Postby twehr » Thu Apr 21, 2011 4:21 pm

cpdude wrote:
twehr wrote:...But being above does interfere, I think, with the front roller on the vrail - see my other post.


Tim, I'm not sure that I'm reading this correctly. Are you saying that having the angle bracket above the extrusion causes interference with the left gantry end bracket? :?

Also, the link provided two posts up doesn't seem to work for me. ;)



The link has been fixed - thanks!

It appeared to me that, if I put the corner bracket on ABOVE the rail, then it would be in the way of me moving the gantry far enough forward to drop the front wheels off the v portion of the rail for installing/removing the lower rollers. It does not interfere with the normal operation, only being able to remove/reinstall the gantry's lower wheels. That is why I left it on the bottom, where I believed it was supposed to go.

That is my recollection of what happened at that time. I could be wrong (yes - it happens).
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Re: Angle bracket/Y axis travel

Postby cpdude » Thu Apr 21, 2011 4:32 pm

@wehr--Okay that makes sense. I'm guessing that would be with both of the Y axis idler assemblies off. I do know that either way (angle bracket on top or bottom) the left gantry end bracket hits the idler before any of the rollers come off the v rail. Anyway, I'll have to try that when I get home.

Thanks,
Brian
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