Clarkson Mark I/II/III Tool and Cutter Grinder - Home Made parts and Modifications






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By Peter Selby :


1. Four Way Swivel Vice
2. Circular bottom plate mod
3. Grinding Wheel Guard
4. Saw Blade Sharpening Attachment
5. Planer/Buzzer Blade Sharpening Attachment
6. Cross Slide Screw Assembly



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↓ 4 WAY SWIVEL VICE


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Here is Peter's description of the vice.

This style of vise can be bought commercially but the ones that I have seen are way too big to fit on the Clarkson so I decided to fabricate one.

The dimensions are:-
Base 155mm x 82mm.
It stands 135mm high and doesn't want to be any taller.
Vise opening 38mm x 12 deep which is ideal to grind tool bits.
The swivels are 75mm in diameter.

Mild steel was used as I didn't want the expense of getting the parts cast or the time delays involved. Materials came from the scrap box.
I have a heat treatment furnace so that was used to stress relieve the weldments.
My Colchester Master look-a-like easily handled the machining, the parts being mounted on the face plate. Other machining was carried out on a Bridgeport clone retro fitted with one of the early CNC kits from Southwestern Industries. Compared to modern CNC mills this is very unsophisticated but performs tasks like pockets, pitch circle holes, etc very well.
There were no cock ups which was rather pleasing as I had only made rough drawings so it was a kinda design as you go.
The really tedious part, and one packed with potential disaster, was the scribing of the 1440+ graduations, followed by the number stamping.
Its so easy to lose concentration and scribe the wrong line.
Yes stamping is not the best method with engraving being a much better method, but I don't now have that option, so stamping it had to be.
Parts of this vice can be used to mount the Clarkson work head.
Note the three sixteenth 3/16 AF Allen keyed grub screws Loctited into the knurled ends of the vise clamping Screws, and the use of .5inch Whitworth bolts, which is in keeping with the rest of the machine.

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Mounting the work head onto the vise base makes the unit much more flexible and with just one spanner needed very easy and quick to set up.
I prefer the 3 jaw for gripping the cutters as I find that the collets due to a few thou clearance do not allow the cutter to run perfectly true.
This is a 100mm chuck which I already had but a smaller one say a 80 mm would be more than adequate and take up less space.
Grinding long series end mills was also a problem solved by making up the plate that sets the work head further back.
Keys are set into the base that align with the tee slots in the table making for quick set ups.
Being able to spin the chuck is also very handy. I have used it for grinding centres and I have ground the seats on ICE engine poppet valves.
I constructed a indexer with six divisions that allows me to grind 6 flute end mills.

 

↓ Here the Universal Head is installed on part of the swivel vice assembly.
Note the detent and indexing ring. They are used to position the chuck.
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↓ Being able to spin the chuck is very handy.
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↓ The unit has to be set back for long series cutters.
Here the unit is installed on a plate that provides the setback.
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↓ CIRCULAR BOTTOM PLATE MOD


On the Clarksons, there is some play when rotating the circular bottom plate. This is because the shank of the 1/2" Whitworth bolt is not a good fit in the hole in the plate, which can cause inaccuracy when rotating and positioning the plate.

Here is Peter Selby's description of his mod to overcome the bad fit:-

To do this mod I had to strip the machine and mount the base plate on the mill to increase the size of the hole to 19mm and just deep enough to press the spigot up to a shoulder.

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↓ The swivel part of the slide also had to be opened out to 19mm.
I machined a flat surface so the whit bolt and washer could seat properly.
While the plate was on the milling machine, I machined the edge of the casting to create a flat and true surface that I will divide up into degrees when I have the time.
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↓ GRINDING WHEEL GUARD


Here is Peter Selby's description of his mod:-

The guard that came with my machine was just a bit of tin roughly bent around, a terrible thing.
Guards have got to be easy and straight forward to fit or they dont get fitted.
I came up with this arrangement.
There are two mounting points so that different areas of the wheel are uncovered.
The guard is fabricated from 3mm plate.
I have one for cup wheels also.

 

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↓ SAW BLADE SHARPENING


Here is Peter Selby's description of his saw blade attachment:-

Saw blades, well the ones that I buy are almost a throw away item but I dont like the idea of that so I sourced a diamond cup wheel, built spacer blocks to increase the centre height and made a spring loaded finger.
The finger has a vertical graduated adjustment that can be used to set the tooth clearances.
The finger is not of my design but one copied from J&S. I have used one for many years and it works very nicely so why re-invent the wheel.
To complicate matters my Son purchased a drop saw which had a 350mm dia blade being too large to fit my centres so two of a larger capacity were fabricated.
The centres are not quite fully machined only requiring the boring of the holes to take the dead centres and a couple of tapped holes.
The mandrel of 1 inch dia was too small for the large blade so I had to make up a washer/ bush.

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↓ PLANER/BUZZER BLADE SHARPENING


Here is Peter Selby's description of his planer blade attachment:-

My 4inch long buzzer blades need the occasional sharpen so I made up this jig.
With the table travel and position of that being wrong I used this ground plate to extend the table.
The plate I made up years ago when I was working as a multi purpose jig which I brought home when I retired thinking that it might come in handy for something.

 

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↓ CROSS SLIDE SCREW ASSEMBLY


Here is Peter Selby's description of the cross slide screw assembly:-

Here is a picture of the cross slide screw assembly that I made up.
I used 4140 material for the screw itself and MS for the rest. Teflon for the thrust washers and of course bronze for the nut.
The threads both internal and external were cut in the lathe using the original size and form.

 

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