New guy from Wisconsin

[EricW]

Hi, my name is Eric. I've been lurking in the diy CNC forums in general for a while now, looking for a design that I like. While there have been a few, this one seems to be couple steps above the pack.

I have never used a CNC but I hope that will change in the next couple years. I'm collecting equipment to start my own brand of snowboards and need an accurate and repeatable method for making cores and maybe some artwork on the top sheets.

So, I already have a question. Most machines I've seen have a gantry that sits vertically vs the horizontal position of this one. Is there an advantage to this or is it just the way it turned out?

[bradm]

Eric, if you think about it, when you push the bit laterally into the material (normal cutting), it exerts force at the end of a lever (the bit, the spindle, the spindle mount) against the Y-Car (and gantry). The problem to solve is how to keep the gantry stiff under these conditions. One way is with very high precision, high strength components. The MechMate way is to distribute the load over a fairly large area to the four wheels of of Y-Car (similar for gantry), which reduces the strength and precision requirements at any one component, which makes it easier and more reliable to manufacture with relatively crude and inexpensive tools and techniques and still get an exceptional result. Now, is this an advantage? You decide. It's a matter of approach.

[EricW]

OK, here's the plan. I'll take any feedback you guys have. My goals for this build are remarkably similar to Jeff's. This will however be part time production machine right off the bat, surfacing snowboard cores and cutting forms for other small builders. I'll be running a 1.5" cutter for the surfacing.

1. 4'x8' cutting area.
2. $3500 budget.
3. Must eventually be disassembled and moved.
4. Accurate to .005". (Ideally but I'd be satisfied with .01")
5. Built as closely to spec of a steel mechmate as possible.

My base table will be build from LVLs. In general I like to build things out of wood since I don't have a welder and I've never done it. I'm a woodworker at heart anyway. I think regular lumber will tend to warp or deflect overtime or during production so engineered lumber it is. They're stable and I think plenty strong for my application. The legs will be standard 2x4.

The gantry will be steel like a regular machine. Since it's basically held down with gravity I want the extra heft not to mention strength. Hoping to start in December or January.

[EricW]

After reading Ross's build I may rethink the wood idea as a way of making the thing movable, provided I can get steel at a reasonable cost.

[smreish]

Eric,
A few successful builds have used wood tables as the base. Using LVL - is a pretty good choice. They are stable, flat, straight and easy to work with. Not a bad choice. But, to be honest, the cost of LVL's, unless your getting remnants from an existing job, won't save you as much as you think....the cost difference might be a couple hundred bucks. I would explore your parts list before making the final decision on table choice.

[MetalHead]

Working on a budget can lead to cutting corners instead of shopping. I say there are two things that get things done. Time and Money. Of course Effort has a play also but the first two usally are inverse of each other. No Time? Better have money... No Money? Better have time.

I say shop your area and contact local metal scrap dealers. Tell them what you are after and check with them once a week. Post on Craigslist that you want to buy scrap steel and give specifics. Also know that steel is not like wood and can be welded back together.

Also keep an eye out on other forums or flat out ask if anyone has Electrics for sale. Some builders can't leave there machines alone (because they did not build a MechMate) and keep changing things.

So if you know what items you are needing and publish these out and about you will find people coming to you trying to unload stuff. That is when you get the bestr deals.

You can see many tables here that use a modified base table. Rigidity is what you are after, and if you can't get the exact steel you can get close. The real tolerence areas are from the X rails up.

[EricW]

Good advice. Thanks.