[zephyr9900]

I guess I have been sleeping. Sometime in the past Tormach started drilling a hole in their TTS-measuring surface plate to accomodate the toolholder shank and eliminate the need for the ground spacer: 31713 - Small Granite Surface Plate with Integrated Tool Hole

What a genius idea! Eliminates one interface in the measurement chain, together with maintaining (i.e. keeping rust-free) the spacer.

I already have two surface plates, and one is the one that came with my TTS set years ago. I know that DIY drilling of granite countertops is commonly done (witness endless Youtube videos) so I figured "how hard can it be anyway?" (I know, famous last words, but this came to a happy ending)

I Googled around and found a good number of recommendations for the diamond-studded core drills from THK (not the esteemed bearing manufacturer, but Treasure Hong Kong) on eBay. $9 with free shipping for three 20mm core drills. 20mm is slightly larger than the .750" TTS shank, so it would be safe, especially with any runout (in this case, to be desired...) Just search for "20mm THK diamond coated core saw" on eBay and you'll find them. The seller even emailed me before the bits even shipped. Very friendly guy and I recommend him.

The bits came in about a week and tonight after work I decided to give it a try. The SOP for core-drilling granite is to build a small dam around the area with plumber's putty and make a little pond of water to lubricate the cut and contain the generated dust. Spent 5 fruitless minutes trying to find my plumber's putty, then decided to make a dam using some camper mounting tape (single-sided closed-cell foam tape).

I chucked up the first core drill in the drill press, turned the spindle on at the speed it was already set at (turns out to be 600 rpm) and applied slight downwards pressure on the bit. It took literally 30 seconds to sink the bit into the surface plate to the point where it wasn't cutting any more. So I stopped and got a small flat-bladed screwdriver and wedged into the cut, tapped it down with my dead-blow hammer and broke off the core, which was easier than I thought it would be.

I soaked up as much of the water/dust sludge as possible with a couple of paper towels, poured in fresh water, and drilled down further. I broke off the second core, and stacking them up it was iffy as to whether I was deep enough. One TTS shank fit in and the toolholder bottomed on the ring on the plate, but I wanted to be extra sure.

I drilled down further, to where the body of the core drill was even with the surface of the plate. I spent probably 15 minutes trying to break off the third core, then decided to drill somewhat deeper to increase the aspect ratio of the core. Then I was able to break it off on the first try. Object lesson: the core needs to be at least as deep as its diameter to be able to stress the base enough to fracture off.

Given my false starts and all, it took less than half an hour to core the hole. I smoothed the entrance with a grinding bit in my Proxxon hand tool and washed the plate off well. I am more than happy with the results.

I did not even begin to dull the first core bit, much less need the other two. I arleady have some small padded envelopes, so if two of you want to mod their plates like this I'll sell the two unused bits for $4.00 each (basically for shipping and trip to the post office) if you PM me.

Obviously, I'll need to redo my tool table, which is old-school measure-on-the-plate-and-type-in-by-hand in Mach3, but it's about time to do that anyway given my tool churn recently.

Randy

[Hirudin]

I too drilled a hole in my surface plate after using Tormach's little plate for a while. I believe I used a 13/16" bit that I found on Amazon. A friend brought over his water-cooled angle grinder and we drilled away. Mine is not as perpendicular as I'm sure yours is, but it's good enough. It really didn't take long or cost very much, and the result is great!

Correction, I used this 7/8" bit...
7/8" Supreme Wet Granite, Marble, Stone Diamond Core Drill Bit 5/8"-11 Thread - - Amazon.com

[rdsi]

Thanks for the post … I've been debating this too & after the mention of TINY plate from Tormach that cinched the deal.
Got myself a diamond hole saw from Lowes (Lenox 3/4”) and did the deed.

Attachment 272088
Attachment 272090
Attachment 272092
Attachment 272094

The final hole size was about 0.785”.
Since I was able to heft it onto my knee mill I wasn't to worried about being perpendicular.
Otherwise, you may need to go up in size.
Also, these drills don't seem to have very good run-out. A few taps with the mallet made it right.
Yeah the drill bit cost about the same as the Tormach plate but the end result is much nicer.

[widget_maker]

What's wrong with just continuing to use the steel collar fixture that Tormach sold before?

[LeeWay]

Nothing really. It just takes a little effort to keep it maintained. It resides under my digital height gauge all the time anyway. I just keep a light oil film on it. 3 in one oil. I do not let any get in the hole though, so that part gets wire brushed every now and then with a gun bore brush.

[brian257]

Thanks for posting this. I got all the TTS tooling and the plate I ordered last week and I just opened the plate last night and sat it by my 12" X 18" plate thinking this little one sure is small, but it is a waste of space. I also wondered if the height indicator I ordered a few days ago and has not arrived yet would fit on the small plate. I will definitely go and drill my big surface plate now. I would have never thought to do that if you didn't post this.

I was going to return the tool tightening fixture I also ordered from Tormach now that I realize that the ER collets have flats and a wrench so it is not really needed. Might try to return the plate also, but it is heavy to ship.

[LeeWay]

Thanks for posting this. I got all the TTS tooling and the plate I ordered last week and I just opened the plate last night and sat it by my 12" X 18" plate thinking this little one sure is small, but it is a waste of space. I also wondered if the height indicator I ordered a few days ago and has not arrived yet would fit on the small plate. I will definitely go and drill my big surface plate now. I would have never thought to do that if you didn't post this.

I was going to return the tool tightening fixture I also ordered from Tormach now that I realize that the ER collets have flats and a wrench so it is not really needed. Might try to return the plate also, but it is heavy to ship.

I would keep that tool tightening fixture. The way it works acts like a ratchet. All you need to change a tool is an adjustable wrench. Open on one side. Close on the other. That thing is one of my best buys I think. I never realized how much easier it actually makes it until I tried it.

[zephyr9900]

What's wrong with just continuing to use the steel collar fixture that Tormach sold before?

For me,

Eliminates one interface in the measurement chain, together with maintaining (i.e. keeping rust-free) the spacer.

Randy

[rowbare]

What's wrong with just continuing to use the steel collar fixture that Tormach sold before?

In my case I have a few tools that are just a fraction too long for my height guage when using the fixture. That problem will go away once I drill the hole.

Thanks Randy for pointing the way!

bob

[vertcnc]

I took my surface plate to a granite counter top shop and they drilled the hole for me. Gave them 20 for lunch and all was good

[MFchief]

I did this today using a 20mm diamond core bit, and it came out perfect. TX Randy!

A side note, if anyone has put off buying as surface plate because the shipping was higher than the price of the plate. Ouch

ENCO is doing free shipping thru the end of March, and it includes truck shipping which is what you will need for a surface plate of any size. The caveat is you need to spend at least $199.00 I bought their inspection grade 18 X 24 with ledges for $205.00 and it came in 2 days which surprised the heck out of me for a truck delivery.

It's an import granite plate of course, maybe not the best around, but definitely good for my skill level.

Terry