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  #1  
Old Thu 20 May 2010, 16:38
silverdog
Just call me: Sergio #70
 
Rome
Italy
Problem with parallelism between rack and rail

Ciao,
Any idea to correct this problem ? shimmering is the best solution ?
thanks
Sergio
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  #2  
Old Thu 20 May 2010, 17:58
Regnar
Just call me: Russell #69
 
Mobile, Alabama
United States of America
Which is not square. The angle iron , rack or both. If its the rack I would seriously give your supplier a call and ask them how they are going to fix it.
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  #3  
Old Thu 20 May 2010, 21:11
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
That is a very strange problem! Is this happening with all the racks and rails, or is it only at some places along the length? Maybe only at the ends? We have seen some cases where the end sections of the racks are badly made, and then it is better to cut off those ends.
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  #4  
Old Thu 20 May 2010, 23:41
silverdog
Just call me: Sergio #70
 
Rome
Italy
Hi Gerard,Hi Russell,
Unfortunately it is like that on all the rails and +/- constant on all the lenght .... the raks are OK
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  #5  
Old Fri 21 May 2010, 02:41
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
If the racks are okay, then the angle iron rails are not okay. You should shim up the point of the rail that is the furthest from the rack?
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  #6  
Old Fri 21 May 2010, 03:20
silverdog
Just call me: Sergio #70
 
Rome
Italy
I think I have to shim up where the screw are and maybe every 50-70 cm using the 3m tape in pieces between the shims, correct ?
Grinding the rack to compensate the angle would be a "dummy" idea isnt'it ?
thanks
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  #7  
Old Fri 21 May 2010, 03:59
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
It would be a smarter idea to bend the motor plates to incline the motors!

I am still trying to understand exactly what has caused the problem? Do you have the same problem with the y-rails on the gantry?
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  #8  
Old Fri 21 May 2010, 04:38
silverdog
Just call me: Sergio #70
 
Rome
Italy
[QUOTE=Gerald D;42388]It would be a smarter idea to bend the motor plates to incline the motors!

I like the sarcastic face ! bend the motor plate it's very scaring to me !!

And yes, all the rail are like that ... the cause is just that the Iron for the rail they sold me was born like that, hopefully all the gantry is squared and the V-bearing rolls very smootly, I'm very happy with that. This is the only real problem I have to solve !
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  #9  
Old Fri 21 May 2010, 04:51
KenC
Just call me: Ken
 
Klang
Malaysia
You got those angle iron for free?
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  #10  
Old Fri 21 May 2010, 05:15
silverdog
Just call me: Sergio #70
 
Rome
Italy
Quote:
Originally Posted by KenC View Post
You got those angle iron for free?
Guess not !
It was my first time !
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  #11  
Old Fri 21 May 2010, 05:24
KenC
Just call me: Ken
 
Klang
Malaysia
Curse the supplier...

Shimming works best when you have many fastening points... I question the benefit of shimming the rack... & bending the motor plate is out of your comfort zone...

How about shimming the motor? shim at the mounting position & tilt the pinion gear straight enough should do the trick.
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  #12  
Old Fri 21 May 2010, 05:32
silverdog
Just call me: Sergio #70
 
Rome
Italy
Quote:
Originally Posted by KenC View Post
Curse the supplier...

Shimming works best when you have many fastening points... I question the benefit of shimming the rack... & bending the motor plate is out of your comfort zone...

How about shimming the motor? shim at the mounting position & tilt the pinion gear straight enough should do the trick.
Wow !!! that would be a very easy task !!

.... yes shimming without many fastening points it's useless
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  #13  
Old Fri 21 May 2010, 05:45
KenC
Just call me: Ken
 
Klang
Malaysia
It is easy in retrospectively... I did not think of that until Gerald mention bending the motor plate...

Anyway, the motor mounting screw fits quite tightly on the motor, you may have to enlarge the motor mounting screw to accommodate the adjustment.
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  #14  
Old Fri 21 May 2010, 07:00
ecki
Just call me: ecki
 
gabs
Botswana
We have same situation on one side x-axis. It's running since half a year daily (and sometimes over night)- no wear and problems yet. Keep it greased ;-)
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  #15  
Old Fri 21 May 2010, 07:30
silverdog
Just call me: Sergio #70
 
Rome
Italy
Thanks,
I think shimming the motor would be a very easy solution without modifying nor the racks nor the rails and very little the plates.
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  #16  
Old Fri 21 May 2010, 10:53
Rascal
Just call me: Rascal
 
Big Lake mn
United States of America
Hi silverdog. Having done much metal fabrication for many years I can tell you the majority if not all your problem is that channel is frequently not square from the outside of the web to the outside of the leg. The same thing is true for angle from leg to leg. Unfortunately angle and channel are structural and not not precision shapes. When purchasing these items bring a square with you and check the squareness of these pieces. In my experience this problem is much worse with materials sourced outside the U.S. I would be very suprised if your rack is not square. Good luck.
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  #17  
Old Fri 21 May 2010, 11:52
Rascal
Just call me: Rascal
 
Big Lake mn
United States of America
Hi Silverdog. I had another thought. Did you attach your rack to your machine with the tape as per the plans?
Could you have a wrinkle or something when you put the tape on? We welded our rack on and perhaps avoided this problem. Just a thought.
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  #18  
Old Fri 21 May 2010, 14:23
silverdog
Just call me: Sergio #70
 
Rome
Italy
Hi rascal,
no the rack are still unmounted so I can still try any solution.
... and yes, all the channel and the angles are not squared ! but only the rack-rails given me problems, everything else is fine.
thanks
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  #19  
Old Fri 21 May 2010, 17:24
digger
Just call me: Milosh #113
 
Toronto
Canada
Sergio, to check what is wrong, rack or channel, simply swap sides of rack - what was closer to 0,0 position, put on far end, and what was on far end put on 0,0. If the problem still exist, problem is channel.

My 2 cents...
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  #20  
Old Sat 22 May 2010, 00:36
silverdog
Just call me: Sergio #70
 
Rome
Italy
thank Milosh, the problem is the channel 100%.
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  #21  
Old Sat 22 May 2010, 03:48
J.R. Hatcher
Just call me: J.R. #4
 
Wilmington, North Carolina
United States of America
Send a message via Skype™ to J.R. Hatcher
My question is .... what problem is this causing? I would just use the machine as is, as the rack & pinion wear they will mate ...right?
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  #22  
Old Sat 22 May 2010, 05:56
MetalHead
Just call me: Mike
 
Columbiana AL
United States of America
I agree with JR. If the teeth of the motor are making a good bite, I would move forward and see if it affects the machine.

Two options I think of is your double sided tape will level this some. Shim only the mounting screw points and when you run the pressure of the motor springs they will push the rack a little more to line it up.

Another option if this is not exceptable is to take the rack and run the back of the rack on a belt sander that is set to a counter the rail angle. Or do that to the rack and flatten it out.
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  #23  
Old Sat 22 May 2010, 05:58
MetalHead
Just call me: Mike
 
Columbiana AL
United States of America
I know it sucks , but I would redo rails making sure the angle I buy is at a solid 90 degrees. But I am picky that way.
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  #24  
Old Sat 22 May 2010, 11:58
bradm
Just call me: Brad #10
 
Somerville(MA)
United States of America
A thought: Which part of the rail is off? Is the milled vertical portion not at 90 degrees to the rest of the table and the floor, or is the rack mounting surface angled somehow?

If it's the vertical that is off, I'm wondering how well your v-rollers are going to track, and if perhaps one of Gerald's metal-shrinking welding tricks could be applied to pull the angle back up.
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  #25  
Old Sun 23 May 2010, 18:53
chopper
Just call me: chopper
 
Big Lake Minnesota
United States of America
Silverdog,
I would do as rascal suggested, the racks appear to be at enough of an angle that just leaving them would appear to cause excessive wear on your racks and pinions, if you for go the vhb tape and weld them on you could shim them before welding them on so they are flat and you are good to go, it would be simple to do and better than the vhb tape anyway, I welded mine on and they are just fine,
bradm, this would be a difficult task to weld and shrink the entire channel or angle rail, not that it couldn't be done, but it would be a lot of messing around to accomplish the same affect by just shimming them straight and welding them.
as far as the rails go they can be tipped a bit with out causing any issues with the rollers since the rollers only contact a very small spot on the top of the rails, as long as you are building it you might as well do it right the first time,
//chopper
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  #26  
Old Mon 24 May 2010, 02:59
silverdog
Just call me: Sergio #70
 
Rome
Italy
Ciao,
First of all, thank you everybody for precious ideas.
I think that more than one option is suitable to solve the problem.
The first one is to bend the motor plates, but you need a professional bender that I don't have nor I know anybody who can do it for me.
Second option is to shim the motors ... this a very easy and forgivable task, anybody can do it even a dummy :-)
Third option is to shim the rack-rail and do a few (3 or4) small weld to block the rack
Fourth option is to leave thing like that if they are not too bad.
Fifth, buy some new "good" iron and do the rails again.
I'm sorry Bradm, but trying to correct the angle with the welding technique can do worst tha the problem is right now (the rails /v-rollers are perfectly matching ...)
I think solution 3 and 2 are the most appropriates for my skill ! :-)
thank you all
Sergio
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