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  #1  
Old Fri 03 January 2020, 14:50
Panovak
Just call me: Paul
 
St. Paul
United States of America
I beams for x rails?

Hi there,
I'm starting to gather materials for the base. I have many large i beams laying around. One size is 6"x6"x 5/16". The other 10"x4"x1/4". I also have a 12"x 6"x 3/8".
Weight isn't a large logistical concern for me however is the 10" height going to throw of the design? Also I like the fact the 12" piece is 3/8 thick.
I've read about how people have used I beams but not any this large.
Thanks
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  #2  
Old Fri 03 January 2020, 14:58
swatkins
Just call me: Steve
 
Houston
United States of America
Quote:
Originally Posted by Panovak View Post
Hi there,
I'm starting to gather materials for the base. I have many large i beams laying around. One size is 6"x6"x 5/16". The other 10"x4"x1/4". I also have a 12"x 6"x 3/8".
Weight isn't a large logistical concern for me however is the 10" height going to throw of the design? Also I like the fact the 12" piece is 3/8 thick.
I've read about how people have used I beams but not any this large.
Thanks

Height is a factor and unless you increase the Z range 10" is too tall. I've seen it stated that the MM was designed mainly as "sheet goods" router and 6" rail height is about optimal. Mine are going to be 8".

I was also reading where there are a few things that would need modifying if you go with an I beam. Off the top of my head is the width would need to be increased to take into account the flange that would be outside the web of the beam.

Then the rack mounts underneath the rail on the outside also. You would have to take that into account as the rail needs to hang over the outside of the I beam and that would make it even wider...


IF you just have to use the I beam I would try this.

Reduce the height of the base legs to lower the top of the I Beam so loading the table would be easier. Then I would cut the top flange off just outside of the web making it into more of a C channel. I would leave the bottom flange alone to keep it as straight as possible. Then to finish it off I would raise the spoil board supports up off the bottom flange as high as 3 or 4 inches and weld them to the web of the I beam. That would effectively make a 6" C channel out of your 10" I Beam and leave the Z , rail mounts and rack as designed.

IF you go that route I would weld the base together before you reduce the width of the top flange.. With the cross supports welded to the web the I beam should not move around too much when it is cut, especially if you use one of the new metal cutting power saws with carbide blades. No mater what you do there will be stresses released when you cut that flange and who knows just how much it will move.

Good luck.

Last edited by swatkins; Fri 03 January 2020 at 15:14..
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  #3  
Old Fri 03 January 2020, 16:35
Panovak
Just call me: Paul
 
St. Paul
United States of America
Thanks for the reply. You brought up an interesting comment regarding the mechmate being mainly used for flat goods. I need to do more research but was actually hoping the added height would help in this regard. I'd like to have the ability to do 3d things.
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  #4  
Old Fri 03 January 2020, 16:50
swatkins
Just call me: Steve
 
Houston
United States of America
Quote:
Originally Posted by Panovak View Post
Thanks for the reply. You brought up an interesting comment regarding the mechmate being mainly used for flat goods. I need to do more research but was actually hoping the added height would help in this regard. I'd like to have the ability to do 3d things.
You can do 3d things

You just have to make a few changes and don't try to carve out the Eiffel Tower

If you want to carve out Eiffel Towers you need to adjust the travel speed because the higher up the router is off the table the less stable it becomes. If the router is 12" up it will not be a precise as a router 6 " off the table, at the same travel speed.

You will also need to change the length of the z so it can get closer to the table if you use high rails.

The beauty of the MM is you can modify it in many, many ways.
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  #5  
Old Mon 06 January 2020, 15:22
Panovak
Just call me: Paul
 
St. Paul
United States of America
I'm using 4"x 2" C channel for the main cross bearers. I'm going to use the 12" I beam and place the cross members within the I beam flange as you stated.
The c channel new would cost 500 dollars and I'd prefer to save that money to use elsewhere. Thanks for your help
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