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Author Topic: Leveling the gantry and table  (Read 11660 times)

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Offline NormB

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Re: Leveling the gantry and table
« Reply #20 on: January 26, 2010, 04:44:20 PM »
Okay here is the DXF file

Offline NormB

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Re: Leveling the gantry and table
« Reply #21 on: January 26, 2010, 04:58:59 PM »
Okay I am in the shop now checking things out.  What I have found is the right side is .021 lower than the left.  That is off the DRO in Mach.  I also found that the center of the MDF is approximately .045 lower than the either end.  The MDF is warped in the middle.  I was told that can't happen.  *L* oh well nice fairy tail.  I know plywood is not better the only thing I know that is strong enough not to bow across 24" is metal. 

I guess I can try to run wood supports across the width to help reinforce the MDF.  Not sure that will work really.  I have to think this one through.

Offline NormB

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Re: Leveling the gantry and table
« Reply #22 on: January 27, 2010, 11:02:01 AM »
I m thinking now maybe putting an aluminium plate on top and cover that with MDF with the T tracks cut into the MDF I could bolt the MDF from the bottom and then level the aluminium plate.  That plate 1/2 thick I would think would be pretty flat.

Offline ger21

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Re: Leveling the gantry and table
« Reply #23 on: January 27, 2010, 05:14:22 PM »
I'd make a bunch of ribs, notched around your screw, running across the table. The more the better. And use 2 pieces of 1/2" MDF laminated together. 4 pcs of 1/4" would be even stiffer. No matter what you use, it'll sag without support.

You should get it as level as possible by shimming, then surface it with the router. I've got a 2-1/2" slot cutter that came from an auction, that surfaces my 30x45 table in about 5 minutes. Amana make a nice surfacing bit, but it's around $200 or more. Her-Saf has a 2" for about $150. Cheapest is to by a 1-1/2" carbide tipped straight bit. About $25
Gerry

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Offline NormB

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Re: Leveling the gantry and table
« Reply #24 on: January 27, 2010, 08:49:59 PM »
I have given some thought about making a frame but had not considered laminating sheets together, my thinking is it might not be as strong, I think you are telling me it's stronger to laminate the pieces.  I know for one thing finding 1/4 is much easier than 1" Even 1/2 is common but 1" is rather hard to come by.  The bad thing is my screw is dead center of the table and would require a rather large notch.  I think I have about 2" between the table bottom and the top of the plate that holds the screw nut.  "With the he aluminium side rails it would be easy enough to mount this frame to the sides with nuts and bolts.  it could become a part of the entire frame.  I have some white oak that is hard as blazes would make a good solid frame but even as you say over time it will warp too. 

I have the table level now I but shims between the bottom tube and the side rail it was only about .021 not much but then the bow down in the middle wow that is about 1/16 from a straight edge placed across the corners and measuring in the center of the MDF. 

If I can get this surface mounted accurately enough might not need to surface the finished top.  MDF is really flat but I am not sure about how flat it will be laminating sheets together.  Will they stay fairly flat? 
Re: Leveling the gantry and table
« Reply #25 on: January 28, 2010, 01:10:27 AM »
NormB

I would keep with an ali plate or a welded frame. i would then mount everything to that.

You will then have piece of mind, novel idea laminating MDF as you say keeping them flat while laminating would be a problem.

Phil
The Good Thing About Mach3, Is It's very Configurable

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Offline NormB

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Re: Leveling the gantry and table
« Reply #26 on: January 28, 2010, 05:26:52 AM »
The Ali plate is by far the more expensive fix but it's permanent.  No more fooling around flat is flat a 1/2 plate is not going to bow and it's easier to mount simply attach with bolts through the top and mount the MDF to that it will take a little space form the Z height but with 5" not going to use all that anyway. 

Offline bowber

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Re: Leveling the gantry and table
« Reply #27 on: January 28, 2010, 03:15:55 PM »
Laminating the sheets to make 1" will be far stronger than 1 sheet of 1" mdf.
To keep them flat while laminating them you just need a flat surface like a table to support it while the glue dries.

You'll be amazed at how much stronger lamination makes sheet materials, I sometimes glue 2 sheet of 5mm PVC to make 10mm as it's a LOT stiffer than the 10mm PVC.

If you then put 1 or 2 supports across the bottom of the sheet that will also add to the strength, all a lot cheaper than an Ali sheet.

Steve

Offline NormB

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Re: Leveling the gantry and table
« Reply #28 on: January 29, 2010, 08:54:47 AM »
Many great ideas, now I have tgo figure out whatI will do from here.  Thank you for all the help ....

Norm