More Bosch Stabilizer Holes

I use a Trent Bosch Hollowing Tool Stabilizer with a fulcrum pin for all of my hollowing.

I am addicted to the fulcrum pin! Using the pin makes hollowing easy, fast and stress free.

However, the fulcrum pin needs to be in the correct location. If it is only 1/8" of an inch to far to the left or right of the hollow form opening then it is no good!

Thus, I like to have lots of overlapping fulcrum pin holes in the tool rest of my stabilizer. So there is always a hole in the right position. I don't like to waste time moving the banjo on my lathe in/out to move a hole into the right position.

Trent's Stabilizer is great. But, it only has 6 fulcrum pin holes in the tool rest. Not enough for me.

After some failed experiments, I sat down with paper and pencil and came up with the hole pattern in this blog entry. It has 16 fulcrum pin holes! I have been using it for over a year and I really like it. My students also really like it.

Carl’s Custom Stabilizer Tool Test

This photos shows the stock tool rest that comes with Trent Bosch's Hollowing Tool Stabilizer on the right. It only has 6 fulcrum pin holes that DO NOT overlay.

My custom tool rest with 16 overlapping fulcrum pin holes is on the left.

With my tool rest you never need to move the banjo in/out to move the pin to a better location. You just move the pin to a different hole in the tool rest.

Different Fulcrum Pin Sizes

The stock Trent Bosch's Hollowing Tool Stabilizer comes with only two 3/4" diameter pins.

I experimented with making different size pins. Larger diameter pins effectively move the holes in the tool rest closer together. Small pins move them further apart.

I made 1/2", 5/8", 7/8" and 1" pins like Trent's 3/4" pin. See photo. The 1/2" pin has a rib on it to prevent it from slipping thru the 1/2" holes in the tool rest.

I also made a pin holder with magnetic base that goes on the headstock of my lathe. See photo.

With my above tool rest hole pattern I really only use my 1/2" pin, once and a while and Trent's 3/4" pin most of the time. I use the 1/2" pin when moving to the next hole with Trent's 3/4" pin is to much.

If you do not want to make my tools rest with lots of holes then you may want to experiment with pins larger than 1" diameter.

The pins DO NOT need to be steel. I made some of my pins out of aluminum. Easier and faster to machine on my metal lathe. Aluminum is strong enough. No problem.

You could probably get away with making the pins out of a hard wood like hard maple.

Top & Bottom of Trent’s Tool Rest

The photo on the left shows the TOP of the stock tool rest and the bolt that is used to attach it to the tool post. The photo on the right shows the BOTTOM of the stock tool rest.

The red arrow in photo points to the TOP of the bolt hole. It is recessed to accept the head of the bolt.

The green arrow in photo points to the BOTTOM of the bolt hole. It is NOT recessed. This is great news! Why? Because, if you want to make your own tool rest you DO NOT need to drill a hole in the bottom to accept the tool post. This makes life a lot simpler.

Carl Ford’s Hole Pattern #2

Click here or on the photo for Carl Ford's Hole Pattern #2 drawing in PDF file.

Print this PDF file on your local printer. Measure the length of the pattern after printing. It should be 1-1/2" wide and 7-1/2" long. You may need to dork around with your printer settings to make this happen. You may need to download the PDF file to get more control over the printer settings.

Raw Steel Bar

You need a chunk of steel bar that is 1" thick by 1-1/2" wide by 7-1/2" long.

Any steel will do. However, your life will be easier if you start with a nice relatively soft chunk of cold rolled steel. No fancy hard stuff. No stainless steel!

The steel I got from my local steel supplier was not pretty. See photo.

Note: I do not worry about rust. A can of WD40 is cheap. A little squirt now and then takes care of any rust. Over time, your tool rest will develop a patina that resists rust.

Pretty Steel Bar

I cleaned up the raw steel bar on my big 6" x 89" belt sander. I also rounded off all the corners. See photo.

I like to use the "Red Label Abrasives 6 X 89 Inch 60 Grit Metal Grinding Zirconia Sanding Belts" sold on Amazon.

You can use what ever you have. Any size belt sander. Or a 4" angle grinder with wire brush or sanding disc, etc.

Attach Pattern to Steel Bar

Metal people would tell you to dye your steel bar blue. Then scratch in your hole pattern. I am to lazy for that method.

I print the pattern out on paper. See above PDF file. Then attach it to my steel bar with some spray on glue.

I like to use 3M Super 77 Adhesive. Any adhesive will do.

Drill Press, Vise & Cutting Fluid

You are going to need a drill press, a vise, and some cutting fluid. This photo shows my setup. Use what ever you have.

I use "Relton Rapid Tap Cutting Fluid" from my local hardware store. You can get it on Amazon. It is not ideal! Because, It is going to smoke a little. I just turn on my dust collector and suck the smoke outside.

The drill press vice in the photo is a Groz UG100-3. See my "Drill Press Vise" blog entry. Any drill press vice will do.

Drill Center Holes

I started by drilling a center hole for each hole with a #2 Center Drill. The little point on the center drill allows you to drill a hole right where you want it.

You can get a "Center Drill Set" on Amazon. Around $14 on 5/5/2021. The quality is not worth writing home about. But they will get the job done.

Enlarge Center Holes

I enlarged the #2 center holes to 5/16" with a #4 Center Drill and cutting fluid.

This step may not be necessary. But, it makes starting a 1/2" drill a lot less fussy.

Drill 3/4″ Bolt Head Hole

The first real hole I drilled was a 3/4" diameter countersink hole for the head of the bolt. Drill it deep enough to hide the head of the bolt below the top of the tool rest. See this photo and next photo.

I used a 3/4" #2 MT shank drill mounted directly in my drill press. Thus, I did not have to worry about the big drill slipping in a Jacobs chuck.

If your drill press does not accept MT shank drills then you can use a 3/4" Silver & Deming Drill in a Jacobs Chuck. See my "Cheap Big Drills" blog entry.

Remember! To avoid a lot of pain. You must always drill large diameter holes BEFORE you drill a smaller diameter hole.

Don't forget the cutting fluid. It keeps things cool and makes drilling a hole a lot easier.

Note: The bottom of the bolt head hole is NOT going to be flat. Like the one in Trent's tool rest. i.e. the hole was not drilled with an end mill. The bottom of the hole is going to be at a 30 degree angle (or what ever the angle is on the end of your drill). This is not desirable. But, in practice it does not really matter. The bolt works. It is strong enough.

Test Bolt Head Hole

This photo shows the bolt head hole is deep enough to hide the head of the bolt below the top of the tool rest. The fool proof, no math, method.

Drill 1/2″ Thru Hole for Bolt

Time to drill the 1/2" diameter thru hole for the bolt. This will be easy, if you drill the 3/4" hole FIRST.

Drill 1/2″ Pin Holes

Time to drill all of the 1/2" diameter thru holes for the fulcrum pins.

Don't forget the cutting fluid. It keeps things cool and makes drilling the holes a lot easier.

Beware! Drilling seventeen 1/2" diameter holes thru a piece of 1" thick steel is going to put a lot of wear and tear on you and your drill press.

Do not overhead the bearings in your drill press.

When the steel bar gets hot. I stop and take a break. I cool the steel bar off in a bucket of water.

Deburr Pin Holes

I deburred all of the pin holes with a 3/4" SINGLE flute counter sink.

If you do not have a SINGLE flute counter sink then I recommend using a hand held deburring tool.

Beware! Multi flute counter sinks DO NOT work for deburring. They will tear up the hole and make a mess.

Finished Tool Rest

This photo shows the finished tool rest. Ready to be installed on my rent Bosch Hollowing Tool Stabilizer.

Glamor Shot

Finished tool rest ready to go.