JGRO Build - Some Assembly Required
After being overwhelmed by all of the different DIY CNC table builds, feature advantages/disadvantages, functions, sizes, etc. I decided to go with a proven winner. Special thanks and a deep bow to JGRO for graciously sharing his table design FREE for the CNC hobbyist.
I decided to go with an almost stock version of the JGRO table and started printing out the plans and acquiring materials over a year ago (Jan. 8, 2005). Today, after much agonizing, sweat, sunburn, blood sacrifices, and late nights, my table is nearly complete. Items to finish include cable beautification, home & limit switches, RotoZip mounting brackets, an enclosure to contain dust, and tweaking.
I'm under no delusions that the end result is perfect. The table could be flatter, it's a little out of square and there is an extra brace for the X-axis roller bearings. It doesn't matter, as it still seems to be more accurate than any drilling and sawing that I can do by hand.
After a request from Jason Marsha, I have decided to document my build in this thread. I'll try to note minor changes I'd make if I had to do it all over.
Off we go,
Launch Pad for JGRO Table
First things first. I built a table to serve as a launch pad for my JGRO build. The table measures 36" x 48" x 22". In retrospect, the table is too small. I'd make it at least 42" x 60" x 22" if I did it over. I'd also make it a four poster (like a bed) so that it would be easier to build an enclosure around it for future dust containment. Table materials are 2" x 2"s, 3/4" plywood, with eight RTC22 corner brackets and SD8X1.25 Strong-Drive Screws made by Simpson StrongTie and purchased at Home Depot. The plywood is fastened to the 2 by 2's using 1 1/2" finish nails.
If needed, extra bracing can be added at a later date.
It's Tapping Time
Time passes and I somehow managed to get all of the MDF pieces cut and drilled. Now it's time for some tapping.
I used 4 flute, high carbon steel plug taps purchased from my local Home Depot and ACE Hardware stores. While these worked I think I should have waited and ordered "thread forming" taps as suggested by other builders of MDF tables. The fluted taps had a tendency to bite into the MDF and actually destroyed some of the threads as it was trying to cut them. For those of you that don't know, thread forming taps do not have flutes or cutting edges. They create threads by displacing the material being tapped. More information on thread forming (or roll taps) can be found at this link: Precision Twist Drill Co., Inc. - Thread Forming Production Taps.
No matter what kind of tap you use to create the threads, make sure you take the extra steps to reinforce the threads with Super Glue.
Use the following procedure:
1. Tap all holes.
2. Reinforce threads with Super Glue. Make sure that you work the Super Glue into the threads and that the threads are coated their entire length, diameter and thread depth. I used a bent paper clip (see attached picture) to force the Super Glue into the holes and threads. NOTE: This is extremely messy and odorous. Make sure you do this outside and over a scrap piece of material. Wax paper may be used to lay the pieces on after the glue has been applied to keep them from bonding to something you'd rather not have them bonded to.
3. Allow Super Glue enough time to properly set. Personally, I'd let them cure for at least 24 hours. Set time for a properly applied thin coat of Super Glue is about 30 seconds. Super Glue globbed into a hole and forced between threads without a uniform coating takes considerably longer.
4. Re-tap all holes. Be careful not to cross-thread any holes when re-tapping them.
5. Sand any surfaces where the Super Glue has been over-applied. Pay extra attention to the tops and bottoms of threaded holes where the tap may have forced some of the glue from the hole and created a "glue burr".
I used approximately 1 1/2 bottles of LOCTITE Super Glue Professional (20 gram bottle, P/N: 01-06921). Seemed to be the best value for my $$$ at LOWE'S.
As noted above, make sure you apply the Super Glue OUTSIDE. Even outside take precautions, sit sideways to the wind direction and allow the air to blow past you rather than blocking it with your back or chest. I didn't have too much of a problem with the odor, but it really seemed to bother my eyes after a little while. And, believe me, this little operation will take quite a long time!
No matter how careful you might be, you will wind up with Super Glue everywhere. Take appropriate measures to minimize the mess and all HEED ALL PRODUCT WARNINGS!!!
I took Sol & Anoel's advice from these 2 threads MDF Sealer and MDF Finishing Question.
Before painting all of the MDF pieces I gave them 2 coats of Zinsser B-I-N Shellac Base PRIMER SEALER Stain Killer (Product No. 00904). If I remember correctly I used about 2 1/2 quarts of the stuff before I was through. I should have purchased a gallon of the primer sealer to start with, instead of 3 quarts, as it would have been cheaper. That's not counting the gas and time needed to keep running back and forth to Lowe's. Not being one who paints often, I never thought I'd need that much. Take my advice, buy a gallon (Product No. 00901).
I used a brush to apply the primer and found it very time consuming. What I should have done is sprayed the primer on the pieces. It would have taken less time, used less primer, and resulted in a better finish.
Zinsser also produces the same primer in a 13 oz. spray can. A bit pricey at about $5.50 a can (Product No. 01008), it would have probably been more cost effective to buy a gallon of primer and a Wagner Power Painter. I could have used the power painter for some other projects. As we all know, hindsight is 20/20.
When priming the smaller pieces I used some 1/4"-20 x 3" bolts and the T-Slotted mounting track (aluminum hold down channel) turned upside down as a drying rack (see pictures).
Cookin' right along,
BTW, when working with Super Glue, especially in this sort of messy application, have some release solvent on hand. At a minimum, acetone-based nail-polish remover, but there is stuff on the market specifically for the job. I've needed to unstick fingers more than once, and when I did it with industrial grade Eastman 910 the nail polish remover wasn't really strong enough.
I have a z axis?!!!?!!?!?! If you and me combine projects we might ahve a complete router