Robot base construction techniques?

Hi all,
Just purchased some expanded pvc for building my robot's base. I will be using a treaded design, utilizing 2 sets of the Tamiya tank tread kit (I
have the nuts and bolts instead of the included hardware for mounting). Just having a hard time figuring out how to get the layout in my head onto the pvc sheet. I was thinking using AutoCAD or another similar software to design the layout, then print and transfer to the pvc? Since doing things just by the eye will probably end up giving me a base with uneven angles everywhere :). Any suggestions?
Sincerely,
Chris Alas
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"Chris Alas"

I just went through the exact same process not so long ago.
First thing I did was to dimension my base drawing to scale all the components I foresee placing on the board. I've used CorelDraw to do that because it is very accurate and easy to work with (at least for me). Some folks prefer Adobe Illustrator but I think CorelDraw is more technical. See the example:
http://www.merlotti.com/EngHome/cpu%20component%20placement%20revB.jpg
Then after making adjustments, I drew the schematics of the platform, including drilling information.
http://www.merlotti.com/EngHome/cpu%20base%20-%20platform%20schematics%20-%20revC.jpg
I'm a huge fan of documentation. It not only gives it a professional look, but also help later if you have to re-design or replace a damaged component.
Just my 2 cents
Padu
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On Tue, 13 Sep 2005 17:28:07 -0400, "Chris Alas"

I don't think you need to mark holes "by eye". Go to Home Depot and buy yourself a small combination square and a fine gradation steel scale. I think you'll find the layout goes pretty quickly with just those simple tools.
BRW
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Bennet Williams wrote:

Sometimes basic manual drafting skills come in very handy.
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snip

snip
Yes, but where do you get a T square, drafting table, iso drawing paper, compass, erraser, geometric templates, drafting paper.... etc.
Just kidding.
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Thanks for the input! I will try out both methods, see which one works for me. thanks again!
-Chris
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Someone who was written up in "Battlebots the Official Guide" was quoted as saying that he used CAD. As in cardboard assisted design.
So I figured "Yeah. Right!"
But I saw it used once and have since come to rely on it when I'm in a hurry.
You just cut, fold, glue, tape... bits of cardboard to make a mockup.
It's surprisingly effective.
DOC

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Just
I use AutoCAD to quickly put in dimensions and drill locations using full size inputs and then print with a ratio of 1:1 which gives me a paper I glue onto whatever I'm to machine, drill or mill. It only takes minutes and is accurate to within a few thousandths of an inch.
Wayne
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I transfer the measurements, starting from a known datum (a straight edge or centre-point) and then draw 6 zillion construction lines. Being good at geometry helps, as does having a good collection of squares, calipers and marking instruments. A square, ruler, compass and pen will do though.
The technique I used at school in the dim and distant past to make PCBs might be easier though - tape a printout of the plan onto the sheet, then use a centre-punch (a compass point may work fine for your PVC) to mark through the plan onto the sheet. Remove the sheet, join the dots and get going with the power tools.
Tim
--
You are being watched. This gives you power.

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Chris Alas wrote:

That's a very good method indeed. You can put a light tack on the back of the paper, and it won't gum up the PVC. The stuff for "make your own Post-its" works pretty well. However, if you get some residue on the PVC it can be cleaned with denatured alcohol. Avoid varnishes, acetone, or other solvents. PVC melts in most organic solvents.
-- Gordon
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I use spray-on adhesives

Just
the
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Wayne Lundberg wrote:

Might be okay. Some spray-on adhesives use a solvent as part of the binder. Expanded PVC is smooth and relatively soft, and solvents will leave pockmarks.
What specific brand do you use?
-- Gordon
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3M Super 77

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I thought Super 77 was for permanent bonds. I think a lower tack is useful for temporarily sticking a paper template to the plastic. I was thinking more like "Restickable Adhesive Glue Stick," which is the same low-tack adhesive they use for Post-Its.
-- Gordon
Wayne Lundberg wrote:

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77 is permanent, and a real pain to remove. Acetone softens it, but put a rag to it then, and it will just smear all over the place.
I don't think I'd want post it glue, it is a bit too sticky.
Glue Stick is a good idea. Washes off with water. AKA paste from preschool....
Rich
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snipped-for-privacy@gmail.com wrote:

Definitely want to keep acetone away from PVC, unless you want to melt it or glue pieces together. Toluene is a pricinple solvent for PVC.
Post-it Glue is water soluble, so cleanup is easy. I think most folks don't use it right. You put it on the paper, then let it "dry." *Then* you stick it on the surface. If it's been appled to the paper correctly, it will not leave a residue. (If it does, a stern letter to 3M is in order. They promise that it won't!)
-- Gordon
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wrote:

I never noticed these problems. I use the 77 mostly on the paper to stick on the detail and after drilling, milling, machining and sawing it's mostly ragged mess that comes off by wiping mostly.
Wayne
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