...rather than a regular drill for making a hole in the WSM's lid?

This message has been edited. Last edited by: tjkoko,

The step drill helps to prevent the porcelain from cracking or chipping since the hole begins smaller with that bit. However, you would use a regular bit if you are careful.

And if you are installing the likes of a Tel-True thermo, the hole actually needs to be pretty large, larger than what most average Joe's would have for bits in the garage or a big enough chuck in the drill.
I did not buy one of the bits myself, I was lucky enough to have a welder friend who had them, and had him drill the hole. The Uni-Bit will still chip the porcelain some. I covered up my chips with a large washer that was also drilled out with a Uni-Bit to fit the thermo base.

Imagine you could start with a small bit and work your way up but I've found that bits like to dance around a bit or tear the metal a little.

Don't really need to use all caps in your subject to get attention either.

quote:

Originally posted by tjkoko:
...rather than a regular drill for making a hole in the WSM's lid?

As already mentioned, it's hard to find 3/4" drill bits for home use.

You can use a step drill bit, which makes for a nice addition to your tool kit after use on the WSM, or you can buy a 3/4" hole saw. You can see an example of that on the More Thermometer Installations page. See "Threaded lid installation", sixth section from the top of the page.

Regards,
Chris

I picked up some step drills at Harbor Freight and the largest size they had was 3/4". I must have drilled at least 30 holes into an 18.5" Bar-B-Kettle bottom and the only time any porcelain chipped was when I forced the bit. I tried a couple HSS drill bits and without using a center punch they are all over the place. I am amazed HD and Lowes don't carry them.

TJ,

I used the unibit # 4 drill as suggested. I expected to drill the hole a lot faster than I did but I think that was due the very old drill that I was using (not much by way of rpms). I did make a nice clean hole. I did have to drill all the way down to the last step 7/8 inch to have the hole large enough to accomodate the BBQ 300 tel tru therm. There was some porcelain chips but I will cover this up with high temp 1000 degree bbq grill paint. Overall, it was definitely worth it.

Why use a Unibit, stepped drill bit??? It's the best tool for the job at hand. If it wasn't we would tell you otherwise.

This is a copy of a post I put up last year about a washer that fits the outside contour of the WSM perfectly. It is available in stainless. If you put one on the inside of the lid it will be self locking so your therm. won't turn. John. P.S. I used a hole saw. Worked great.


Posted August 18, 2006 09:17 PM Hide Post
Hey guys, I new and kind of anal about stuff but since I am a mechanic by trade I thought I would share this. After drilling the hole I installed a Belleville Disc Spring over the hole before installing the thermometer. A belleville has the same curveature as the Webber lid. You can check them out at Gardner Spring. You will need part number mb1750-057-S. They are stainless steel and come six to a package. Do a google search on Gardner Spring. Enjoy and tell me what you think. John.
Posts: 23 | Location: Chico California | Registered: August 02, 2006

This message has been edited. Last edited by: John Chips,

What follows is the reply that IRWIN, manufacturer of step drills, sent to me. And just disregard shat's stated pertaining to the drill size.

Terry, all three bits are starting and finishing bits. They just start
and end at different sizes. You can if needed drill with one and finish
with a larger size bit.

I forwarded your e-mail to our metal drilling engineer who has worked
with UNIBITS many years. Following is his response to your drilling
question. He says the bit marked #1 would be the best to use. As it
finishes with a 1/2" size hole you can drill the hole with the single
bit.

"The #1 is the best bet. Since the single flute tip goes to the center
of the drill it will create a point that will chip and break thru the
hard porcelain layer. From there it will drill through and the smaller
steps will open the hole easier.
Now this is very important. USE A VERY SLOW RPM WITH A HEAVY FEED
PRESSURE!! Since the porcelain is very hard and can not be cut, it must
be chipped and broken away as the bit rotates and the hole is enlarged.
A high RPM will cause the cutting edge to rub too much on the porcelain
and dull the cutting edge which then will not cut the steel.
A center punch could also be employed to help start the chipping and
breaking of the surface at the entry location.
Use the #1 to complete the hole. The quality of the finial hole should
show a slight amount of chipped porcelain around the hole but this would
be minimal."

Let us know if you have any other questions.

That's interseting - low rpms is better. In my case, the porcelain chips were indeed very minimal and were uniformly located around the hole. I did have some difficulty beginning the cutting process as the bit was trying to break trhough the porcelain. It seems to make more sense to use a center puch to begin the chipping process. WHile I was drilling, I was applying a lot of pressure to the bit because it did not seem to cut easily. The results were good but I thought it would cut more quickly. I suppose that it speaks to the quality of the material used on the wsm.

I got my Irwin #4 Unibit from ebay, brand new and delivered to my door for slightly less than $25. How 'bout the rest of you?

Home Depot...about $34.00

It was pointed out that the belleville disc I refered to in an eariler post was mis-identified. I went back and corrected the number. Sorry about that.
I will post a picture as soon as I can figure out how. John.

This message has been edited. Last edited by: John Chips,

Just installed my Tel-Tru with 4" probe via the Unibit #4 method. Started with a nail to scribe my point of attack and liked to have had a cow when the porcelin chipped just a tad bit. Then drilled just a small starter hole, then inserted my brand new Unibit#4 for that scarey moment. Everything turned out great, thanks to this sites guided instructions. Just be sure and use a variable speed drill and run it kinda slow. Firm pressure and let the bit do the work. I, like most on this site, had never used a Unibit before.

Good luck!

Dino:

In drilling the pilot hole, did you use high or low rpm? I believe that drilling into metal requires low rpm.

I agree with Dino’s approach (except for the scribe part) especially with the variable speed drill run slow to medium speed. I installed Guru adapters on both my Ranch Kettle and 2nd WSM using a very small drill bit for a pilot hole and then a slightly larger bit before using the Unibit. I used painter’s tape on the inside and outside, ran the variable speed drill approx. 25% applying some, but not too much pressure. On the RK, I used no oil and found the bit got pretty warm by the time I was finished so I used oil on the WSM but it was just as warm. I noticed no difference between the holes and saw no chipping, inside or out.

Bill, I center punched, trying to keep the bit from wondering. I tapped it with the fear that the porcelin might chip and it did ever so slightly. I did tape when it came to drilling.
Did you have trouble with your starter bit wondering?

Dino,

I’ve read here where others have “center punched” and more often than not, the porcelain chips since it’s so brittle. I feel it’s really not necessary. I used a 1/16” very sharp drill bit in a variable speed drill, steady the drill bit against the porcelain with the middle/ring finger against the grill/smoker and the thumb right next to the chuck on the drill and started off very slowly, 3 revolutions/second or so and increased speed from there. Keep the drill bit perpendicular to the porcelain surface and you should have no wandering. Install a larger bit, 1/8” or so that will accommodate the smallest size of your step drill bit (Unibit) and enlarge the hole. I think the key is like you said ~ Light to moderate pressure and slower speed. I believe the tape also helps.

Bill

Thanks Bill, look to get another WSM on down the road, and I'm sure this will help.
By the way my starter hole after center punching was a 1/8th bit. I guess the whole porcelin thing is what worries most of us.
We have all drilled a little wood and metal, but this porcelin thing is a little scarey to rookies like me.

Thanks again!