Re: Home built machine setup, perpendicularity

I have not heard of Shars yet. I jumped on their web site and they
have some attractivly priced items.
I might try setting up with a small square I have initiall but
leave myself open for small adjustments as I use the table.
Thanks for the reply.
Scott

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Leslie Watts"
<leswatts@a...> wrote:

> Hi Scott
>
> I use a large 24" machinist's square and an indicator.
>
> SHARS used to sell these in accuracy class H in a fitted wooden

case

> for only $99. I have lab grade granite surface plates and granite

square to

> check
> these on and found them quite accurate...within tenths. You have to
> carefully control
> temperature to measure such things. I bought several.
>
> I checked their site to get a link for you but they seem to be out

of stock.

> J&L has them but the price is $250 and they are advertised as only

workshop

> grade...
> much poorer perhaps.
>
> You can play games with Pythagorus and such or generate three sets

of

> precise squares
> if you have a very accurate surface plate but it takes a lot of

time.

>
> Hmm....no economical large squares out there...I have thoughts of

making

> some for sale. Perhaps 24x36" or 36x 48"? Class H? I could do

that...

> but surely not for $100. Not $1000 or something like a Starrett

either.

>
> Leslie M.Watts
> L M Watts Furniture
> Tiger Georgia
> (706) 212-0242
>
> Main page:
> http://www.lmwatts.com
> Engineering:
> http://www.lmwatts.com/shop.html
> Cnc surplus for sale:
> http://www.lmwatts.com/forsale.html
> Carved signs:
> http://www.lmwatts.com/signwp.html
>
>
> -----Original Message-----
> From: CAD_CAM_EDM_DRO@yahoogroups.com
> [mailto:CAD_CAM_EDM_DRO@yahoogroups.com]On Behalf Of Scott Riddle
> Sent: Thursday, July 07, 2005 9:59 AM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: [CAD_CAM_EDM_DRO] Home built machine setup,

perpendicularity

>
>
> I am looking to put together my own home built CNC machine with
> linear rails and ball screws onto a heavy tube frame. I am trying

to

> figure out how to drive the main X axis which will move a gantry
> over the table. I am contemplating using 2 ball screws(smaller

ones)

> to drive each set of trucks. This way I can assure no racking
> problems and have increased machine stiffness. My main questions is
> if I go to the 2 screw system and I am using stepper motors how do

I

> initially when build this machine get my X and Y axis

perpendicular?

> Assuming that each X and Y rail setup is straight to start with.
>
> Basically can I measure perpendicularity on a 3' x 3' linear rail
> setup with something like indicators. I do not have access to any
> large right angle plates or things like that. I would think that
> there would be some clever way to measure this.
>
> I used to design machine tools for several years so I know all the
> basics but when we did this setup part it was all done with a

laser.

>
> Thanks
> Scott
>
>
>
>
>
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