Thread: Brooks TC Grinder.

Hi Familyguy,

Thank you for your question, its not obvious why a collet would be used on a control knob.

Originally Posted by familyguy

Just wondering why you went for a collet system to secure the knobs to the lead screws - do you intend to make the knobs easy to reset to an index mark.

I have a bunch of instrument knobs (salvaged from old electronic equipment) that use the same method to secure them to a shaft.

Got it in one ! Plus grub screws tend to cockle a knob over to one side slightly, so when rotating you get the knob rubbing on one edge.

Yes grub screws are not great, my biggest issue with them is that they will often raise a burr on the shaft making it difficult to remove the thing that the grub screw is securing.

My first lathe was older than vintage - I'm guessing around 1890 - 1900, probably antique, it had seen little use, no wear on the bed or lead screw, I soon found out why, it was impossible to take even the lightest cut with out chatter. I eventually traced this down to the method of fixing the headstock to the bed, a single 5/8 bolt through the middle of the headstock tightened up against a strip of 1/8" mild steel. Amongst the things that needed to be done to the lathe were the top and cross slide handles, the originals were long gone and replaced by old victorian style tap handles fixed with a grub screw, the ends of the top and cross slide lead screws were machined to take a handle with a square hole and I wasn't sure how to machine a square hole through a handle boss, but a toolmaker friend of mine suggested tapers so I eventually made new proper machine ball type handles and fixed them to the shaft with tapers, it was well within my limited capabilities at the time.

My Quorn uses a large collet to secure the tool indexing ring to the tool holder, it works well - easily tightened and easily released.

Hi Guys,

I made this pin wrench yesterday to be used for tightening the securing plate nut on the end of the collets that I'm going to use to secure the knobs for the X - Y table adjustment, and the angle adjustment worm drive.

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I used a 50 mm length of 18 mm diameter silver steel rod. I've not yet to put a tommy bar hole and securing screw in the other end. I need to find some suitable bits of material for that. That threaded hole in the end is a left over from what ever I was doing last time I used this silver steel rod.

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I turned one end down to 9 mm diameter for a distance of 7 mm and then single point threaded it with a carbide threading tool, 1 mm pitch. ( M9 X 1 ). I also wanted to practice this thread ready for when I thread the end of the collets, yet to be made. Note the run out groove, I just used the rear parting off tool to put a 2 mm wide 2 mm deep groove at the bottom of the thread. I also turned off the excess 1 mm after I had threaded it.


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This is the business end of the wrench. It is a collar of a 6 mm thick slice of 16 mm diameter leaded steel bar, drilled 7.8 mm and tapped M9 X 1. The idea being that it would screw onto the end of the wrench and I could use the drilling jig that I made, to drill the pin holes. Those pins are 2 mm diameter silver steel, hardened using a cooks torch and then tempered. Much easier than trying to drill the end of the bar accurately.

Those pins turned out far too hard to saw to length, so I used an abrasive disc and the Dremal to cut two 9 mm long pieces. The ends were chamfered using the pin held in the drill press chuck and pressed into a piece of broken grinding wheel. The pins were locktited into the holes in the collar.

Well that sorts out the bits needed to fasten the collets ! Next job is to actually make them.

Thanks guys, your participation is appreciated. Thanks for looking.

I’ve been following along for a while but struggling to get the concept of how all these parts will come together. Are you aiming for the original pic posted or something else?

Fascinating read and I’m super engaged as will be trying something to sharpen drills and end mills myself at some point, but I suspect a lot simpler (and likely less capable).

Hi Neevo, Thank you for your post.

The original Brooks Grinder caught my eye because of its potential utility. I also could see various problems with the way it was built. I approached the design with several goals in mind. One of which was cost ! The use of precision ground rods sliding steel on steel seemed wrong somehow, not withstanding the considerable cost of precision ground steel bar. So the answer is yes ! The original purpose of the machine is that of a universal grinder with the ability to do precision work.

So I looked at various alternative ways to make the machine more easily and much less costly. I chose to go with ball races because they were cheap and easily available, I also had them in stock, which helped. After that it was almost all measuring and machining. I think so far that I've only spent about £40 in bits and pieces. A lot of the material that I've used came from Engineering works scrap boxes or the scrap yard. Some of which I've been given and some that I've had to buy in.

The parts that I'm working on at the moment is the control knobs for the spindles. The last few posts have been all about using and making collet fittings to secure them to the shafts.

I've tried to show how I've done the things that I have and how they have worked out, mainly in the belief that the information contained is helpful.

Whilst I am an Engineer, both Electrical and Mechanical, I only started machining as a hobby after I retired ! I've learnt an awful lot from this forum, for which I'm very grateful.

As far as grinding drills is concerned, I started trying to learn to do it by hand ! I've never completely managed it, so I made various jigs to help which made it more likely that I would get a good point. With encouragement from people on this forum I made the four facet drill grinder from "John Moran's" Gadget Builder web site. This is one that I would highly recommend ! You wouldn't believe the difference a well ground four facet drill makes.

Hi Guys,

I've done the drawing for the drilling jig to make the pin holes in the plate nuts for fastening the collet onto the control shaft and into the knob.

Plate-Drilling Jig.png 07-03-2020-002.jpg

Note: Machine the body to size first and also the top plate. Mark out and drill the top plate before drilling any holes in the block. If you drill the fastening holes in the top plate 5 mm diameter first, you can align the two pieces to accurately drill matching holes into the block then these holes can be tapped M6. Afterwards open out the holes in the plate to 6 mm so the fastening screws can be fitted through.

If done well, there will be minimal play between the two. Also note the outer pop mark ! This was done to ensure that the top plate was the right way up and the right way round. There is a corresponding pop mark under the plate. The little dimple in between was already there.

As can be seen in the second picture, I drilled three 2 mm holes in the top plate, using the centre one for setting up the block for boring the 16 mm recess. After boring, the centre was drilled out 9 mm clear to allow the drilled plate nut to be removed. The two outer 2 mm holes were then drilled using the holes in the top plate as a guide.

In use the turned and threaded 16 mm diameter plate nuts are placed into the recess and the top plate fastened down. This has the effect of securing the plate nut in the recess preventing any movement whilst drilling the pin holes. Once the pin holes have been drilled the plates may be tight in the recess, so the tap or threaded mandrel can be used to remove it.

I also used the jig to make the pin wrench as previously described.

Thanks for looking Guys.

Hello to Baron J.
https://www.youtube.com/watch?v=qsQOyqdNCdI
This link goes to a video on a TCT grinder. Using a good bench grinder the accessories open up what you can sharpen.
Hope this helps
BC

Hi Guys,

I was given another scrapped shower pump yesterday, usual problem sized up. Anyway I've taken it apart, found that its a universal brush motor, rated at 254 watts. Quite a small rating compared to other pumps I've aquired.

The Left hand side pump, the hot water one, has leaked water into the pump bearings and caused it to seize up. Interestingly this particular pump also has a variable speed TRIAC controller mounted on the top of the motor case. The motor also has thermal protection built into it, so there has been no damage to the motor at all.

Its actually quite well made ! It is not riveted together like a lot of other motors I've seen, and the ball bearings in each end are very common 6000 series. So no problem replacing them.

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This is a picture of the motor complete with the impellers screwed on either end. The black one is for the hot water. They are also quite thin only 8 mm thick, the plastic sides take up 3 mm of that. The water enters through the centre of the impeller and is forced out of the edge. The pump is rated for 2.5 metres of head.

This motor has long 8 mm diameter shafts coming out at each end, which suggests that it could be a candidate for driving a wheel head spindle.

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This is the speed controller. The mains supply goes in at the bottom middle of the picture and the motor is connected to the two pins at the top right hand side. The blue capacitors and the cylindrical black things are an interference suppressor designed to stop the sparking of the motor brushes causing radio and TV interference.

The speed control knob is in the middle opposite the mains input. Flat out the motor spins at a respectable 12,000 rpm, slowing to about 6,000 rpm with the control knob at minimum.

Thanks Guys.

Hi Guys,

I've been figuring out how to make the collets for securing the control knobs for the grinder.

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The collets are going to be made from 1/2" inch diameter brass bar. This was made as a test sample in order to work out how to produce a number of them all identical. This was turned and drilled directly on the end of a length of bar placed in the soft jaws of the lathe chuck. The hole through is 6 mm diameter and the body was turned down to 9 mm (0.354" inch) for a distance of 12.5 mm. The taper was done with a square ended form tool set at 12 degrees before parting off. I've not threaded the end yet because I want to put it into an ER32 collet in a square collet block in order to slit it. I'm making the assumption that dividing it into four segments will be enough, the alternative is to use the hexagonal collet block and divide into six segments.

So I now have my pattern !

More to do on this front, make a sample plate nut slit and thread the sample.

Thanks for looking Guys.

Hi Guys,

Having now made a 6 mm bore brass collet as a pattern, I've now done what I should have done and made a mandrel to put the collet blank onto. The mandrel will be held in the lathe chuck and used to turn 20 mm long brass blanks with a 6 mm hole drilled through them into collets.

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This is a picture of the mandrel. It is made from the shaft of a broken half inch Whitworth tap. You can see the square end it the pictures. It must have taken some force to break one of those ! I didn't break it, honest, it was in a box of bits that I had picked up somewhere.

Anyway I've tempered the whole thing by leaving it on the top of an upwards facing gas heater burner for around 5 hours, then leaving it, letting it cool overnight after turning the gas off.

It machined quite easily, turning it down to make a 6 mm diameter spigot, and it was easy to drill a 3.2 mm hole in the end and thread it M4. Actually it was much easier than I had expected and much better than throwing it into the scrap bin.

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This is a family picture of the bits needed to produce this mandrel. Apart from a brass blank, the Allen key and the M4 cap screw. I made a tiny steel collar that was turned to 9 mm diameter and drilled to clear the M4 screw. I then made a 2 mm wide shoulder turning it down to 6 mm in diameter so that it would fit into the end of the brass blank. I parted it off at 7.5 mm long. This was done so that the brass blank once placed on the mandrel could be secured with the cap screw, ready for turning to 9 mm diameter and the tapered cone put on the end. Once the collet has been slit, it can be placed back on the mandrel ready for threading with a 1 mm pitch thread,

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These last three pictures show the assembled mandrel and some different views of the parts used.

I'll do a drawing for this later.

Thanks for following along guys, its nice to have your company.

Hi Guys,

I've done a drawing for the mandrel showing all the parts, including a brass collet blank.
Collet Mandrel 1.png

I'm going to make a collet using silver steel in order to make a tapered cutter to machine the taper in the aluminium knob bore. At the moment I'm contemplating making a "D" bit or a four flute cutter then hardening it.

Thoughts anyone !

Thanks guys.

Hi Guys,

First a couple of pictures that I forgot to post earlier whilst turning the sample brass collet.

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The tool bit that I'm using is a broken 3 mm HSS drill stub, ground into a left hand lathe tool.

Next:
After turning a collet in silver steel and finding it difficult to actually hold it sufficiently firmly to mill half the taper away to make a "D" bit, I decided that whilst the idea of a "D" bit was OK, it was wrong in the way that I was doing it. So a change in strategy. I did a drawing of a four flute cutter to make the taper.

Taper tool.png

The drawing shows a short length of silver steel with the taper and a short spigot on the end. If I mill four grooves in the taper it should cut the same taper in the aluminium knob material. The whole idea being to be able to make a number of identical knob collet assemblies repeatedly.

Can anyone see any flaw in this idea ? Seeing as my earlier one didn't quite work out as intended.

Thanks for your attention.

Hi Guys,

I have had a go at designing a simple grinding spindle ! I've done a drawing that shows the basic design, there is nothing shown for the ends of the shaft since I haven't decided how I'm going to mount the grinding wheel or how I'm going to drive the shaft.

Spindle Design 1.png
The overall cartridge length is 150 mm or six inches with a 31 mm diameter and a 12 mm diameter shaft. I have used four 6801ZZ bearings, A: because they are cheap from China and B: they are only 21 mm in diameter, allowing the cartridge body to be quite small in diameter and C: they are also only 5 mm thick.

I've used 15 mm long tubular spacers to secure the bearings and to set the distance of them apart. They are secured in the cartridge body at one end and are secured on the shaft at the other. I intend to use threaded caps at either end with felt dust seals under the cap.


Thoughts or suggestions anyone, thanks for looking !

Thanks guys.

Have you thought about toothed belts to drive it? I have some of these on their way from China for my bandsaw reduction drive. They would be perfect I’d imagine if they are as I expect.

Hi John.
I've probably misinterpreted the drawing, but what locates the shaft axially? Are you just relying on a press fit of the bearings to the shaft since there's no shoulder on the shaft?
Is then intent of the inner spacer at one end and outer at the other to be able to adjust preload?

Steve