[Master_Arvist]

Any updates?

[steve123]

Any updates?

As a mater of fact, yes!

I made 8 brackets out of 1/2" x 4" angle. I welded in triangles to eliminate flex. I then machined the two faces flat and perpendicular. I got a 1/2" carbide end mill for this. That was a pleasure to use!
Attachment 289806 Attachment 289808

I then started in on the bushings that are the upper attachment of the two main X beams to the granite surface plate.
First I made 8 bushings on the lathe. These are 1" steel.
Attachment 289810
Those fit in 1" holes I drilled in the beams. My brother and I welded them in.
Attachment 289812 Attachment 289814 Attachment 289816

[steve123]

I finished up welding the gantry legs. Those are 3/8" and 1/2" steel now.
Attachment 289818 Attachment 289820

[steve123]

I made 3/4 x 1.5" stainless (303) inserts. These pretty much look like the ones I have seen on the web. These will be epoxied into holes in the granite plate. I will drill and tap the shorter ones after they are in place. The longer inserts will stick out 1/2". The brackets I made earlier have grub screws to allow vertical adjustment of the X beams.
Attachment 289822 Attachment 289824

[steve123]

Drilling Granite!
I wasn't sure how this would go, and it took some doing. I have 20 holes to drill! I start with purchasing a very high quality water swivel and diamond drill bit. As I recall, they cost about $220 together. Diamond Core Drills, Universal Application - Call (661) 257-2288 I also got a 1 gallon pump sprayer and some tubing to connect it to the water swivel from Home Depot.
I really abused this water swivel and bit, but they just kept working.
Attachment 289830

I laser-cut a template from 1/4" plywood. Here I have it clamped to the side of the table.
Attachment 289832

I did a small test spot with the cordless drill with the water going, and found that I really couldn't keep the drill straight. It has a (very slow) bubble level on it, but I would wander up and down anyway!
This was NOT working. I wanted to use something like what I used to know as a portalign AccuDrill Drill Guide | Toolmonger I couldn't find one that had a 1/2" chuck. They are just too small and whimpy. I decided to make something. Here is what I came up with in about 20 minutes.
Attachment 289834
The drill guide is made from a scrap piece of 3/8 plate, with a piece of 3/4 rod welded into it. I welded a piece of angle to a heavy wall pipe. I drilled holes in the angle spaced out like the grease nipples of the water swivel. As you see, the water swivel is attached using the grease nipples. The pipe was a little larger ID than 3/4", so I added some grub screws. Now we have something that I can clamp on. It won't go anywhere, and the drill will stay straight!

[steve123]

How to finish drilling before I am an old man?

I started out just pushing on the drill. I couldn't keep that up. I next tried this:
Attachment 289842

The string trimmer line runs across to... A half full 5-gallon bucket.
Attachment 289844

I drilled that way for 15 minutes with very little progress, even with me leaning on it. I need more pressure!
Attachment 289846

Even with the extra weight, it took 26 minutes to drill the first hole! OK I will be an old man before I finish 20 holes!

This is what I ended up with. A clamp! This is just before starting a hole. I just turn the handle slowly, and the water coming out of the hole turns to milk! Stop turning and it goes clear again.
Attachment 289848

How long to do a 1.5" deep hole now? 5 minutes. Fastest time was 2.5 minutes. I kept it to 5 minutes, hoping the bit would last for 20 holes.

Getting the core out is just a matter of inserting a screwdriver and tapping it lightly with a hammer.
Attachment 289850
If it didn't break off at the very bottom of the hole, just reach in with the screwdriver to the bottom edge of the hole, and twist. I started to realize just how brittle granite is.

Results! A total of about 7 hours drilling. Faster next time!
Attachment 289852 Attachment 289854

How does it fit? Great!
Attachment 289856 Attachment 289858

Now for hole cleanup and epoxy!

[steve123]

I blew the holes out with compressed air, and sprayed them with the pump sprayer, and blew that out. I also got a tubing brush from Harbor Freight and used it in a drill. I am going to stuff some damp cloth in there and spin it around also.

What epoxy to use? I found out that they make anchoring epoxy. One of the good ones is Redhead G5. It comes as a double caulk tube. You screw a mixing nozzle on the end.
Attachment 289860

I had a hard time finding these at a good price. Grainger wants $230 for the gun! Amazon sellers wanted $5 each to ship each nozzle.
I ended up buying the G5 epoxy for $25.76, The gun for $40, and 6 nozzles for $20 from Ebay. Tomorrow I will do the final cleaning, and give the epoxy a try.