Diary of a FoamCutter building a jgro router table

[Glidergider]

Well here I am, bitten by the CNC bug. First its a CNC Foamcutter, now a Router. Besides cutting wings, I've had equal fun cutting foam art. See the example below.

First off, a big thanks to jgro for the most excellent plans. Its been said by many folks in this forum, and I'll repeat it again. Wow, the plans are great, easy to understand, read, and simple to build.

I started with the two base assemblies. They went together easy, cutting the components with the table saw. The two subassemblies are glued but not nailed. I'm likely to use drywall screws instead of nails. Is that ok, or should I just use nails?

Not much to see yet. I'll make some progress in the evenings this week. But I have only Monday thru Friday to work on it, then a two week break, as I'll be travelling for work.

Me and a co-worker (John Miller) got the CNC router bug while discussing CNC topics at the coffee pot. Its entirely Johns fault that I'm building this table. John is also building a jgro. I'm hoping that John will show us his progress as well. By the way, John is a far better craftsman then I, so we can expect a higher grade of work from him.

Wish me luck.
Dave

[mcyr]

Hey Dave, I recognize you from RCSE. I've caught the bug with this CNC router stuff, too. What are your plans to use the router for...DLG wings ala the Encore? Or bigger stuff?

Mike

[Glidergider]

Mike,
Jon Stone is a fellow NASF club member. As you know, a great guy. I cut that foam trophy for him and will present it to him on Tuesday. So, if you see him on RCSE, please don't tell him about my creation. Too many Jons/Johns in this world. Too many Daves also.

Its a small world!
take care,
Dave

Originally Posted by mcyr Hey Dave, I've caught the bug with this CNC router stuff, too. What are your plans to use the router for...DLG wings ala the Encore? Or bigger stuff? Mike

[Glidergider]

Mike,
I'm planning to cut and bag a 3 meter. I'll probably use the Supra airfoils and planform. Then, add a big carbon spar and bag it. Too bad though, this CNC router project is putting a big delay into those build plans. I've also cut a couple DLG wings for a buddy, but the 3 meter is my next big build project. If, that is, I can clear my head of this CNC router bug. (not likely to happen).
Dave

Originally Posted by mcyr Hey Dave, I recognize you from RCSE. I've caught the bug with this CNC router stuff, too. What are your plans to use the router for...DLG wings ala the Encore? Or bigger stuff? Mike

[HayTay]

Originally Posted by GliderGider I'm likely to use drywall screws instead of nails. Is that ok, or should I just use nails?

Screws, nails, brads, paneling nails, doesn't matter, just test whatever you're going to use on a few scrap pieces of 1/2" and 3/4" MDF to make sure that it's not going to split. Don't forget to predrill holes for the fasteners to reduce the chance of splitting the MDF. The only problem with using screws and nails is that they have a bigger head which means you'll have a better chance of hitting them with another fastener when you attach subsequent assemblies/pieces.

Watch when you measure and drill the Gantry Front (CNC_DTL20). The three vertically aligned holes on the left and right sides should be spaced at 0.375", 1.438", and 2.500" to match the bolt and dowel pin holes in the Gantry - Left Side (CNC_DTL16) and Gantry - Right Side (CNC_DTL17).

Another thing, I just switched my X-axis and Y-axis leadscrews from 1/4"-20 allthread to 1/2"-10 ACME screws, 1/2"-10 ACME nuts, and DumpsterCNC A/B nuts, what a difference it makes. You wouldn't believe how much faster, smoother, and quieter the JGRO table runs after switching from the 1/4"-20 allthread. If I would have known that to start with I would have made the modifications for the larger ACME threaded rod and skipped the alltread altogether. Some modifications to the design must be made to accomodate the larger diameter thread, bearings and dumpster nuts. Just my 2 cents if your interested.

You've made excellent progress, so far. Keep up the good work.


L8r,

[Glidergider]

Hi HayTay
Thanks for the tips. I'm amazed how cheep the 1/2" acme hardware costs. I'll be making that modification for sure. Also, I will be predrilling the holes before any fastener gets attached. Thats good info. I appreciate the heads up about the dimension changes.
Dave

[jem1043]

Well Dave, you are making great progress. I have purchased some MDF but that is all. Because my garage is not heated and there is a woodworking show in Atlanta this weekend, I will not make any progress for awhile.
I sure agree with the comments from "HayTay". Pre-drill all fastener holes and the 1/2/10 Acme threaded rod are the way to go. We'll get these built someday. Keep up the good work. John

[mcyr]

Hi Dave,

I'll be watching your progress on this thread. I'm thinking about building a cnc router myself for the purpose of routing elliptical planforms with transitioning Drela airfoils that would be impossible with wire cutting. I'm most interested in DLG's and Sp400's so a smallish router might do the trick.

So many projects, so little time! Good luck with you build.

Mike

[Glidergider]

Mike,
I've always wondered how a CNC router would finish the bottom of a wing? See the attached picture. The top is no problem, there's no easy way to finish the bottom. What would you do? You can't turn a complex airfoil on

Now if I were cutting a foil for a mold, then no problem, because you would cut a top, the cut a separate bottom.
Dave

[edo]

If the problem is laying the wing flat when you turn it over, can't you cut a "mold" to lay it in? It should be easy to invert the code used to cut the airfoil. Don't know how you'd do it with a wire, but this may be just one more reason you need to build the router.

[Glidergider]

EDO,
Heres a German group that cuts their cores with a router. They cut both the top and bottom half side, by side. Then the wirecut each foil at the parting plane, glue them together, and waaahhla, they have a wing.

Actually they go further and vacuum bag these wings in a mold.

http://www.delago.de/ariane/ETechnik.htm
and
http://www.delago.de/ariane/EStyro.htm

Interesting.
Dave

[Glidergider]

Hey John,
The bearings arrived.