Re: are 3/4 shafts good for axis ?

My plans are to do wood working. making simple signs, like house numbers. ( think large individual letters)

my maximum tool will be a trim router.

I have a CNC mini-mill, so I have no need to attempt to try to do metal.

The cost of 4 BishopWisecarver bearings and needed rails would bump the cost of this machine higher than I would like.

I have started looking at taking 2 skate bearings, mounting them on a 45 and using home ground steel (also on a 45) as the rail. I know this presents tremendous hurdles. one is parallel installation of bearings and rails.

Since I am only expecting 2-3 inches of Z travel, I hope that round shafts would not be a problem. I thought about a 6 inch travel, but that would be for foam cutting for lost foam casting. I thing anything would work for cutting foam !

Of course, I am re-designing to allow a simple swap out in the future in the event I am not satisfied.

I seem to remember a second source for Vee bearings and rails. now it seems that only bishop wisecarver offers them. I wonder if there was a patient infringement ???

Anyone know where to get hardened Vee rails for a decent price ?

I am not adverse to getting more than I need. I have a second (smaller) machine in the future.

Dave

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Jack" <freshwatermodels@...> wrote:
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> Dave,
>
> Three key questions- What sort of tollerances do you need to hold and
> what sort of finish do you want? What do you want to make? Axis
> travel length would also have some impact on the rail.
>
> I have a retrofitted mill and a home made 3 axis router. Both aren't
> like a big rock solid closed loop servo unit but they serve my needs.
> Much depends on what you are making and the tollerances and finish you
> need. Another issue is feeds. I can't hog material at 30ipm on my
> machines but then I don't need to.
>
> My shop is geared to make things and I don't build, buy or use a machine
> with out considering what I am going to make and the cost involved.
> What one fellow considers a junky machine might serve another fellows
> needs.
>
> Most of what I make on my little mill are tiny metal casting patterns or
> simple parts which have to be reasonably accurate. The parts I make on
> my less than precision router are fine if they come out within a few
> thou or fit together properly. In both cases I sometimes tweek my
> program to get more accuracy. Often I run a few test parts, measure
> and then tweek the program and run the parts.
>
> Build a machine that fits your budget and needs. If this is mostly
> just for fun, build cheap and do some learning before you spend the big
> bucks on building the dream machine.
>
> I buy parts off eBay and have had pretty good luck. I especially like
> Thompson "super slides" which seem to be a good value on the used
> market. I also use Thompson 5/8" transportation grade ballscrews with
> reasonable results. Most of my parts are less than 12" long though I
> often rout them from 24" long planks.
>
> Jack
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