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  #1  
Old Sat 24 April 2010, 06:07
bonny
Just call me: Bonny
 
Sencur
Slovenia
MiniMechMate?

Hello...

I want to build MM. Sem's ok and working.
Thus I have question if I can deviate.... And how much.
I need the smal cutting area 50cm X 110cm X 10cm.
My workshop is in attic and I must carry all thing by hand to the.
Here are few laser cut shops but are expensive so I want to get rid of it and use some stock materials. I have question if the gantry can be made lighter as is short. My intention is to use thick wall square tube 50x50mm and for Y rail support to use rectangular 100x40(or 50mm) tube instead of C.
The other question is if I move gantry beams close (just to have place for Z rail and router) how much that can affect performance?

Thanks.

p.s.
I know that is MM forum and my intention is something betven MM, shopbot, Ez.... So moderators can erase that message without feeling guilt.
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  #2  
Old Sat 24 April 2010, 11:35
KenC
Just call me: Ken
 
Klang
Malaysia
Welcome,
This might be helpful
http://www.mechmate.com/forums/showt...=baby+mechmate
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  #3  
Old Sat 24 April 2010, 12:37
isladelobos
Just call me: Ros
 
Canary Islands
Spain
Send a message via MSN to isladelobos Send a message via Yahoo to isladelobos
I not think the mechmate is the best desing for a small table with this.
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  #4  
Old Sun 25 April 2010, 05:07
KenC
Just call me: Ken
 
Klang
Malaysia
Ros, I agree with you, but there will always be someone who disagree... very strongly...
Even if they build one, the foot-print to work area ratio won't be meaningful.
BUT like everything else, everyone are entitled to their own believes...
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  #5  
Old Sun 25 April 2010, 12:51
bonny
Just call me: Bonny
 
Sencur
Slovenia
Hello again..

I'm already build CNC machine and is capable to do whai I intend to do. But it's only 30x20cm. I can drill and cut PCB and this is main job for "her". Of course it dig in alu front and backplate without problem. Brass part's come out realy nice. So I try to put some angle iron in it and try to route it. No problem at all! Just need to replace router (woodrouter) to some better thing for iron. The drawback is small area and slow cutting speed (1080mm/min).

Now I want to make windmill blades. Not big one but usable. So I start new build and soon realize that I make to much mistakes. So Now I search the web to find some proven plan. And I get the MechMate as a good candidate. Strudy cheap not some $$rails and works.

So I just thinking and realize that I can swap XY and use gantry as is just shorten table. So my intention is to make something with 1100 x 600mm size and capable to have 4 axis.

But now I must have decission. I want speed. The mechmate gantry can be for 2meter table too. So As I have only half of that I thinking I can scale down parts (cost) too. And of course no laser parts. But want to preserve rails. And Read that some users have made own V rolers from plastic and brass. But don't know if I can scale down bearing to (22x7x8mm - rolerskate)

... just probably miss forum. Probably with only V rail idea and way how to grind it my machine doesn't deserve MM name

Slavko.
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  #6  
Old Mon 26 April 2010, 01:00
bonny
Just call me: Bonny
 
Sencur
Slovenia
Quote:
Originally Posted by isladelobos View Post
I not think the mechmate is the best desing for a small table with this.
I want to ask why?

And just to refresh what I want.
1100 x 600mm cutting area
fast and deep cutting (big router as spindle not dremel)
accurate to aprox 0.1mm
durable
and of course cheap
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  #7  
Old Mon 26 April 2010, 02:59
bonny
Just call me: Bonny
 
Sencur
Slovenia
Does somebody know for some good calculator for beams deflection?!?

I found this one on net.
http://www.calculatoredge.com/civil%...lator/beam.htm

But output seems to be wrong or MechMate is not as strudy as I think.

I just enter aprox parameters for gantry beam and I got:
Lenght 60"
Width 2"
Height 4"
Thicknes 0.158"
Force 100 pounds
and got that beam deflect 0.0657502" ?!?!

Someone know what is wrong? The parameters? The flexing MechMate or just calculator is bad.

very thanks for answers
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  #8  
Old Mon 26 April 2010, 04:25
KenC
Just call me: Ken
 
Klang
Malaysia
how did you come up with the 100lb force?
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  #9  
Old Mon 26 April 2010, 04:34
bonny
Just call me: Bonny
 
Sencur
Slovenia
Quote:
Originally Posted by KenC View Post
how did you come up with the 100lb force?
With my small machine the motors stalls at 600N force on spindle axis. And if I plunge router too deep I can reach the point that motors stall. Can't do that in MDF but in oak is pretty easy. So 100lb is even smaller.

I wan't to know what real force on cutting tool is but have no clue how to calculate it. But I think the 100lb is in MechMate range. (worst case)

Or maybe I'm wrong?
Slavko.
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  #10  
Old Mon 26 April 2010, 04:55
KenC
Just call me: Ken
 
Klang
Malaysia
I have no idea how to come up with the correct force...
the deflection figure is good for 60" span... did you consider 2 beams? & what figure did you expected to see?
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  #11  
Old Mon 26 April 2010, 05:04
bonny
Just call me: Bonny
 
Sencur
Slovenia
Quote:
Originally Posted by KenC View Post
I have no idea how to come up with the correct force...
the deflection figure is good for 60" span... did you consider 2 beams? & what figure did you expected to see?
Huh...
I consider 2 beams.
... and I calculated for only one. But I got in account only force. The weight of beam alone is big too.

And expect way better results. (factor of 10)
And 60" is smalest gantry for MechMate.

What result's you got from MM? What accuracy of PART you have?
Maybe I'm just expect to much...
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  #12  
Old Mon 26 April 2010, 05:27
KenC
Just call me: Ken
 
Klang
Malaysia
you are expecting 0.0065" over 60" is +/-0.000054" per +/-0.00065"inch or +/-0.0013" per ft... its still too loose for building jet turbine blades but too accurate for making PCD or home furniture...

Suggest you dig this forums seriously, there are a wealth of info, & most question in your mind (particularly this one) had already been discussed & beaten to death.
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  #13  
Old Mon 26 April 2010, 05:31
bonny
Just call me: Bonny
 
Sencur
Slovenia
I'm expect 0.1 to 0.2mm part accuracy. Is that achived with MM as is?!?
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  #14  
Old Mon 26 April 2010, 06:42
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
When people expect accuracy, they do not take the final cut at the stalling load of the router.

Yes, you expect too much from a low cost machine.
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  #15  
Old Mon 26 April 2010, 07:02
bonny
Just call me: Bonny
 
Sencur
Slovenia
Quote:
Originally Posted by Gerald D View Post
When people expect accuracy, they do not take the final cut at the stalling load of the router.

Yes, you expect too much from a low cost machine.
I know that that load is for very rought roughting. And final pass is near with NIL force on router.

So is it 0.1 to 0.2mm in reach of MechMate?
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  #16  
Old Mon 26 April 2010, 07:48
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
0.1 is in easy reach.
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  #17  
Old Mon 26 April 2010, 08:09
bonny
Just call me: Bonny
 
Sencur
Slovenia
Quote:
Originally Posted by Gerald D View Post
0.1 is in easy reach.
Ok thanks.

What do you think is best.
To use gantry as is (and swap XY to have short table) or to scale everything down and use the gantry as short axis?

btw do you think the roler skate bearing (22x7x8) can handle loadings two in V sleve. And MM use V sleve aprox 45mm in height is shortening to 30mm wil affect wear to much? I read somevhere in forum that W2 wear quick. How quick?
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