Building A Tool Post Grinder

Mark_f

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Since I have had the need several times lately for a tool post grinder, I have decided to build one because a good one is wayyyy expensive.

I will start by making the spindle first, since it is the heart of the tool and must be of good quality. I intend to use the Broadley spindle design. It uses Belleville washers to set the 10 lbs. of preload on the angular contact bearings.

I ordered angular contact bearings ( the same bearings I used in my Bonelle grinder spindle). They have a 20 mm bore , 47 mm OD, and 17 mm wide. The reason for this bearing choice is because I can , and did, get a ER 20 collet chuck with a 20 mm shank and 5 1/2" long. MY SPINDLE IS ALREADY MADE FOR ME :grin:. The chuck is pretty hard and ground, but cuts ok using carbide tooling.
image.jpeg image.jpeg
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I put the chuck in an ER40 collet and threaded the end 28 TPI.
image.jpeg

Next I made a steel nut to fit the chuck. The chuck is already sized for the bearings. I will relieve the center area. This is the easiest spindle I ever made.
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I have ordered a piece of 2 1/4" OD round 12L14 steel bar for the spindle housing.


Keep watching.......
 
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Been thinking along the same lines myself . Among all the other thoughts in my head.
 
Spindle Assembly.jpg This is a drawing for the tool post grinder spindle. It will use two single row angular contact bearings with a 20 mm bore, 47 mm OD and 14 mm wide. There are four bellville washers in series to provide the ten pounds of preload on the bearings. The body will be made from 12L14 steel bar stock 2.250" diameter and 4 1/2" long. the end caps to hold the bearings will also be made from the same bar stock.
Spindle Body.jpg This is the print for the spindle body.
turning spindle body.jpg I have drilled the bar stock with a 15/16" drill and will bore it out to 1.400 inches , cut the OD to 2.200" and bore the end for the bearing. then it will get turned around in the chuck to bore the other end for the bearing and bellville washers.

more to come....
 
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Maybe getting ahead of this but how will this mount to the toolpost? A piece welded on to the spindle housing? I copied your two drawings.
 
Maybe getting ahead of this but how will this mount to the toolpost? A piece welded on to the spindle housing? I copied your two drawings.
Recopy the spindle body drawing . errors have been corrected.

No... I don't weld anything if I can help it. I have a couple methods in mind , just not sure which I will use yet.

The height will be adjustable in a small range to adjust wheel height some.

The most important thing is to build a good spindle first.
 
I spent the day working on my spindle for the tool post grinder.
Turning the Spindle Body.jpg I bored the housing to 1.400"through, then bored the O.D. to 2.200". I then bored the bearing recess to depth and size for a hand press fit. I also threaded the end at 32 TPI for .300". It is important that everything is finished at the same time before turning it in the chuck to do the other end. This insures concenticity.
Finished Spindle Body 2.jpg The body was then turned around and this end was finished in the same manner.
Spindle Parts 2.jpg End caps were made to screw in the ends of the body. The photo shows the Spindle body parts. the body, end caps, bellville springs, and bearings. The print is for the end caps.
Spindle End Caps.jpg
Assembled Spindle Body.jpg The parts are all assembled to check everything for fit. The next order of business is to fit the spindle to the body before final assembly.
Assembled Spindle Body 2.jpg
Oil Seals.jpg The oil seals ( national #471224) Were bought at my loal auto parts store for $4 each. The end caps have a counter bore on the inside for the seals.

More to come..... finished Spindle Body.jpg Spindle Parts.jpg
 
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I have finished my spindle and it came out great.
spindle 4.jpg
spindle 5.jpg These are photos of the finished spindle. I made my pulley from aluminum only because I didn't have a piece of steel the right size. Since the spindle was pretty hard and can't be machined with HSS I could not cut a key way. ( i ordered a carbide end mill but I don't know when it will arrive.) I came up with a good method of installing the pulley. I threaded a portion of the inside of the pulley so it screwed on the spindle and up against the bearing. I made a recess in the outside of the pulley and the round nut I made earlier screws on the spindle and up against the pulley locking everything in place.
I am including the prints again here as THEY HAVE SEVERAL CORRECTIONS! These prints have the correct numbers in theory for the spindle but when machining, we can be off a couple thousandths here and there. This can add up, so to make sure everything fit up tight and my preload is correct, I made the end caps .300 long instead of the .250 on the print. I screwed the front cap in tight against the bearing and measured the gap. I then machined this amount less .005" off the end cap. this let it screw up tight on the body and against the bearing. I assembled the other end and measured the depth to the bearing. I added the .040" needed to compress the bellville washers and machined this amount off the cap. this let it screw up tight against the bearing and body and set the preload. This made a nicer looking spindle and i don't have to mess with shims as the original design had.
Spindle Body.jpg
Spindle End Caps.jpg
Bearing Spacer and Pulley.jpg
Now that I have a good high speed spindle, I can make the rest of the tool post grinder.

....MORE TO COME
 
That is an absolute work of art, Mark....very well done, thanks for sharing-
 
Now that the spindle is done, it is time to make the base to hold the spindle and motor. The base is made from two aluminum blocks I found Together they make a 4 X4X3 block. I drilled 4 bolt holes to bolt them together.
drilling base.jpg I chucked the blocks bolted together and drilled a pilot hole through, then followed with a 1" drill.
boring base.jpg Next I bored a hole that is a close slip fit for the spindle.
rough milled base.jpg A couple hours on the mill to square up the block and milled a notch in the center and I have a roughed out base for the spindle. There is more work to do on this piece.
 
Here are some photos of the spindle and the base. I chose aluminum for the base to keep the weight down some. I want to be able to pick the thing up and put it on my lathe :grin:.
spindle and base 1.jpg
spindle and base 2.jpg
spindle and base 3.jpg I'm really happy how this is turning out so far. I have a 1 1/2 HP tread mill motor I will be using for the motor on this project. it is small and light and has a speed of 4800 rpm. it is ideal. I have ordered a small digital tach that will mount in the switch box to show the speed. The unit will be fairly compact and light compared to some tool post grinders.
 
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