How accurate of a machine can be made from wood? I am considering building a small 3"x6" slide table (x/y positioning device) but ultimately it will have to be accurate to .001 so I am thinking I would be better off in some sort of plastic or metal...
I have bought and have made animation stands with that kind of accuracy. Material was 3: of mdf with 2 part resin between the layers. It makes for a very stable base.
Take a look here...
So to answer your question - yes you can as long as you use the right materials and plan accordingly. Your design needs to include a zero reference capability in both the x and y axis. Even if you make it out of other materials you still need a calibration capability.
Bob S.
The device you seem to want sounds like a slightly larger version of the mechanical stage used on microscopes to position slides at very high magnification, such as 1000x. While I don't recall the exact parameters, I do know that it's possible to locate a single bacterium, remove the slide, do other things with the scope, then replace the slide and re-locate the same bug within seconds.
To be fair, one usually reads the stage verniers relatively grossly and then homes in on the subject by using landmarks within the field of view, but a good mechanical stage is a fairly decent precision instrument. Other manipulators allow one to insert an extruded glass syringe into the middle of a single nerve cell - or an ovum. Good enough?
If you need more range than one of these stages can provide, could you attach it to a moveable base that would allow you to position it grossly, lock it down, and then use the finer capabilities of the stage itself?
You can go all the way from this low-end device to spending beaucoup de bucks on a Zeiss. Also, don't overlook the used market. There are loads of companies selling relatively inexpensive high-end microscope products in outstanding condition that have been re-cycled, damaged in some way that won't matter to you, reconditioned, upgraded, etc.
DanD
What's a "vernier" screw? Sounds like what I could have used. I tried to build a... um? A focusing rail? A flummy to mount on my tripod to let me slide my whole camera forward and back in teeensy increments, in order to focus one of those macro/zoom combo thingies more easily. I built it out of aluminum bits, pop rivets, and a couple of carriage bolts. It never did work to my satisfaction, and I've since recycled all the bits. I could still use one though.
Velmex makes good slides that are inexpensive (that's relative) and functional. You can buy various configurations and there are a lot of selections and engineering tools on their site. Try this and see if it will fit your needs:
HF has one, as does grizzly. as to their accuracy, that's another story.
At this point I am just trying to create a free moving x/y positionner, that I can butt against a pair of micrometer heads, and feed an item held by a small vise into a rotating cutter. All I was asking was that if I made the slide-table aspect of this from wood or whatever, how accurate could I get and not be affected by the material. I am coming to believe that something like a steel dovetail way slide will be necessary, and that will make the whole idea cost prohibitive. Of course, I may be fine with a small milling table, but I am still looking at sources on those.
If you are actually interested in the actual project, I will be happy to discuss it in email, as I am not sure it pertains to woodwork, especially if I don't use wood to make it :)
Thanks, I see grizzly's but the only thing I come up with at HF is the cross slide vise. I will have to see what the precision is, and how easily I can remove the vise :)
Dan --
I'm sorry, I really wasn't trying to be as vague as it seems.
What I am attempting to do is an improvement on an existing product. It is a machine that is used to make keys from a brass blank with a steel cutter, by knowing the cut position and cut depth. Currently it works on the principle of a carriage that rides on a rod. It is stopped (for depths) by a micrometer in front of the carriage. It can be controlled laterally by rubbing it against a micrometer to one side set to the current position. It is fed into the cutter by a movement best described as an arc.
I am trying to come up with a replacement for the carriage to 1. feed straight into the cutter instead of on the arc. 2. Make lateral positioning and forward movement more accurate and convenient.
I am currently researching about 3 or 4 different methods of doing this, including stepper motors and actuators, dovetail way slides, milling tables, and a few really oddball ideas. At some point there is diminishing returns as this is approximately $300 machine (not really though) and the next better machine is about $1600. So as the costs rise to improve it, the benefits of doing so decease.
-- Absinthe
Harbor Freight cross-slide vise 4x7" travel, $25, Table play guaranteed to be less than 3/16"...once it's fine-tuned.
- - Let Exxon send their own troops -
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Are you familiar with Grainger?
DanD
positioning
They did....
Knobs, Cranks and Hand Wheels."
Can I borrow some money? I think I need to spend some time browsing here.
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