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Member postings for John Hinkley

Here is a list of all the postings John Hinkley has made in our forums. Click on a thread name to jump to the thread.

Thread: Solving Engineering Mistakes
22/07/2019 15:34:24


Without knowing the design of the tool, I was just throwing a few ideas into the ring! Think of the washer idea as similar to using one of the Teflon-style coatings used to refurbish machine ways. Twenty thou is pretty thin - a piece of brass shim that thick secured with superglue would probably withstand what little load there is on the tool when in use.  ( Even if it meant machining a bit more off to accommodate it .)


Edited to add the afterthought in brackets.

Edited By John Hinkley on 22/07/2019 15:36:02

22/07/2019 10:19:58


If I have understood your predicament correctly, instead of "adding thickness" to the side plates, I would personally remake the mating pieces in thicker material to 20 thou thicker. They look to be the easier to construct and from less expensive stock.

Is the fact that there is extra clearance that critical? Depending on the construction, a large brass, or similar, washer might take up the "slack"?

There's more than one way to skin a cat. I have no doubt others will come along soon with more ideas.


Thread: TTFN
18/07/2019 16:42:35

I, too, echo the sentiments expressed by all those above. Keep reading and I'm sure you'll be back before long. I want to know when your traction engines are finished, at least.

I seem to remember a forum member by the name of John Stevenson used some mighty industrial strength machines ( and industrial strength words, on occasions! ) but no one lambasted him for that! I think he would have had short shrift with them, had they done so.

Best of luck, whatever you decide and keep away from the "cumulo-granite".


Thread: Milling a T slot - am I doing it right?
12/07/2019 12:12:44

Nice one, Neil. Elegant or not, if it does the job then that's fine. It's the result that matters.

I managed to reduce the cutter shank as I outlined above and the resulting profile looks like this, the original on the right and modified profile on the left :

cutter comparison

I wasn't able to replicate the production tansition slope with the setup I had, though with a bit of fiddling and changing angles, I could probably get it a lot closer.

Graham - you should be able to see from this shot that the teeth are staggered, so it really is a tee slot cutter!

After applying all the advice given, to a greater or lesser extent, I've finished the tee slot and am pleased with the result. Thanks to all who contributed. I have to say, tee slot cutting is not my most favourite procedure and I will try to avoid it in future designs.


11/07/2019 18:21:04

A quick update for those interested........

The new cutter arrived yesterday, too late to do any serious work with it, but today I managed to finish off the first cuts. Unfortunately, the shank of the cutter fouls the top of the tee slot when lowered to remove the lower portion of the tee. I'm going to try to grind the shank down to match the section behind the cutter to obtain the required clearance. In the meantime, I've sharpened the old cutters using the setup below:

sharpening setup

It works quite well and produces a good, clean cutting face.


09/07/2019 17:33:35

Graham, Dave and Hollowpoint,

All good, valid points and I will try to incorporate all your suggestions. We've been out all day visiting York and when I got home, found that the new cutter hadn't arrived, so hopefully it will come tomorrow. As for clearing the chips, I'll have to rely on a brush and the Vax vacuum. I think I'll slow the feed rate down a little and also the cutter speed and see if that helps. Time, if not on my side, is not of the essence.


08/07/2019 12:45:49


No, no cutting fluid, just a squirt of cutting oil as it progressed. I don't have compressed air in the garage, either, having given away my compressor when we moved back to the UK. The chips are coming off hot, but not blue, enough to be painful when they land on my hand. I stand back a bit further, now, while wiping chips away with a brush.



Edited By John Hinkley on 08/07/2019 12:46:41

08/07/2019 12:16:02

Nicholas and Andrew,

Thank you both for your input. I'll try all the suggestions and report back. For further info - the Mill is a Warco VMC - so reasonably substantial with a 1½ HP 3-phase motor/VFD combination fitted by me. No rev counter fitted so I'm just going by years of looking at engines idling at 800rpm to estimate the spindle speed!


08/07/2019 10:41:20

Here's a quick one for you. I'm in the initial stages of making a cylindrical grinding attachment for my surface grinder. It involves milling a tee slot along a piece of 70mm x 40mm BMS. I've started by creating an 18mm deep x 12mm wide slot without problems, although I did buy a carbide 10mm roughing end mill to do the major metal removal. To mill the cross "T" part, I've used two of my tee slot cutters in the set up shown below. Progress is painfully slow and at about one third down the slot, the mill actually stalled. My question is: am I using the tee slot cutter correctly or should I be nibbling away at the cut with a smaller diameter cutter? I should add that both cutters have previously only been used on cast iron and looked to be fairly sharp. ( Not now, though! ) I'm using a spindle speed of, I estimate, 5-600 rpm and feeding at about 150mm/min. I've ordered a new cutter from Arc, which ought to arrive tomorrow, but I thought I'd make this enquiry on here, before using it in anger on Wednesday.

Tee slot cutting


Thread: Gear Measuring
30/06/2019 10:07:00

Just for fun, I "fiddled" around with GearDXF and scaled your original photo in QCAD, then roughly overlaid the outline of a 25 tooth gear generated by GearDXF. The other parameters - for no good reason apart from that's what the program worked out, given the number of teeth - were pressure angle 20°, tip diameter 64.022mm, pitch diameter 59.8mm. These figures give a MOD of 2.371. It gives an approximation, within the limits of the photo, thus:


The yellow line is obviously the gear outline from GearDXF. It doesn't quite match, but it's close, if you take into account parallax, etc.

Good luck with your search.


29/06/2019 14:12:38


You might find this data reference sheet a useful download. I use it as an "aide-memoire" from time to time as I infrequently make gears and am easily confused by the various terms. There is no guarantee that your gear is a MOD one, of course, it could be an Imperial size.

Maryland Metrics gear data

And while I'm at it, the technical data section of that web site has a whole host of data sheets - some more useful resources than others, here:

Technical data index

Alternatively, you could always have a fiddle about with a gear-generating program such as this, which I use to make dxf files for CAD:



Edited By John Hinkley on 29/06/2019 14:13:25

Thread: bridgeport power feed
24/06/2019 14:12:34

I can confirm what David has already stated. The power feed unit I purchased from Warco with my VMC mill came complete with a casting to mount directly to a Bridgeport. No modifications appear to be necessary and full instructions were included in the kit.


Thread: Is CAD for Me?
21/06/2019 19:13:39

I have followed this thread from day one and contributed what I hoped was an encouraging post. All I hear now as I read on is a constant "swish - thwack, swish - thwack, swish - thwack.." It's the sound of a dead horse being flogged.


Thread: Historic Frogs
20/06/2019 11:58:03



Thread: Warco WM16 machine vice
20/06/2019 10:32:26

I originally purchased a swivel-base vice to go with my mill but the swivelling part was ditched in pretty short order, never to be used. I sold it after a while and replaced it with a 100mm verstaile SG vice from my favourite Leicestershire emporium. Actually I ordered a 160mm one, only to find out it was far too big and heavy for my mill and nearly gave me a hernia trying to lift it onto the table. Luckily, I was able to return it straight away and trade down to the smaller one. You might have trouble mounting it longitudinally, if you needed to. Personally, I've never found the need. I do, however, find that the alternative vice jaw positions can provide useful solutions to intricate workholding problems on odd occasions.


( Warco VMC mill, not a WM16 user. )

Edited to correct spelling

Edited By John Hinkley on 20/06/2019 10:33:30

Thread: How have Apple found out my new Debit Card number?
20/06/2019 10:17:01

My wife and I were issued with new credit cards when the bank informed us that some people were experiencing security issues with theirs. We weren't, but accepted the new cards. I dutifully went to all the accounts I had with various businesses and changed the details. When I got to PayPal, I could find no way to edit the card details, except, I found later, by delete the existing card and go through the rigmarole of setting up a new one. It transpires that my credit card issuer ( and many more besides ) have an automatic system to update your details with traders holding your card details without your intervention. That's what happened, although it didn't happen overnight - if I remember it took about a fortnight for the change to occur.


Thread: Metal Bandsaw - Chester H80 or Warco CY90
18/06/2019 09:24:06

What Trevor said. Don't expect it to cut true straight out of the box. Most, if not all, will reuire a little tweakery to cut square and vertical. I would also recommend fitting a bi-metallic blade. They are, in my opinion, superior to the factory-fitted one. Tuffsaws supplied mine and I've had no trouble over the last eight years of ownership.


Thread: Making High Speed Steel Injector D Bits
17/06/2019 10:21:01

As an aside:

Posted by Andrew Johnston on 17/06/2019 09:30:28:

Back when I was working on racing cars the engine manufacturers spent hours smoothing and polishing the inlet manifolds with die grinders. Then it was discovered that a slightly dimpled surface, that caused some turbulence, was better.

Isn't this why golfer's balls have dimples? Makes them go further and faster, I think. I would have though it might be interesting to experiment with dimpled upper surfaces of aircraft wings to speed airflow and therefore increase lift. And the reverse for racing car wings. But then, I failed aerodynamics at college - maybe that's why!


Thread: What Did You Do Today 2019
15/06/2019 13:42:28

I finished a couple of mods to my simple indexer today. I've made up a mild steel plate the same dimensions as the base plate and fixed it to the indexer so that I can use it on the surface grinder. ( The original base plate was aluminium - 'cos I had some! ) The idea was to use the indexer as a rudimentary form of cylindrical grinding arrangement while amassiing the material for the real thing. Also to grind the points of the engraving cutters for the secondhand engraving machine that I recently purchased. The detent screw locating the reference plate is released and the machine handle, attached to the outer plate provides the rotation. The pictures say it all, really.

Cylindrical grinding setup.

Angle grinding setup

Before anyone comments - the pictures are posed to demonstrate the positioning of the indexer only. I don't intend to grind on the side of the mounted grinding wheel. I have just received a deep cup diamond wheel for that but haven't fitted it yet.


Thread: Dro scale positioning
13/06/2019 19:22:52

At the risk of repeating what I've put in similar other posts, I overcame this problem by extending a milled bar beyond the scale on my VMC:

x-axis scale 1


x-axis scale 2

The travel stops are retained, too. More pictures in my album.


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