Here is a list of all the postings John Baron has made in our forums. Click on a thread name to jump to the thread.
|Thread: Wall Chart|
Cromwells do a free on request A3 size one on a paper backing,
Worth a phone call !
|Thread: Old lathe tools|
Hi Dan, Guys,
I would pinch the knurls from the push knurling tool and make a pinch or scissor type tool to use them on. The knurls on those are usually good quality ones !
|Thread: Setting up rear parting tool properly|
This is a picture of my "Norman" patent rear tool holder with a 12mm X 2mm blade in a holder. It is horizontal and set exactly at centre height. The tool holder can be used on the front tool post as well.
|Thread: 12 volt motor speed controller|
Hi John, Guys,
When I built my window screen wiper motor driven mill table drive, I used a variable voltage lab type power supply. Mine supplies 30 volts at 3 amps. I just use the whole 30 volts for fast traverse and around 7 volts for actual milling.
My direction control is via a tumbler gear very similar to the one found on a Myford lathe, giving me forward/stop/ and reverse directions.
This is a picture of mine mounted on the left hand side of the table. I just pull the white knob out and lift or lower the lever to select the direction or neutral. It also has the advantage that I can still use the handwheel at the other end when neutral is selected.
All the gears were salvaged from printers. photocopiers and the like. The motor unit is a "Trico" one salvaged from the local scrapyard.
|Thread: Taps and Dies|
Yes I bought a metric set from them quite some time ago ! Good quality, but I didn't pay today's price, in fact if I remember correctly only about £4.00 + vat, vat was only 15% then.
I've started to buy my taps and dies from
Good quality HSS UK made.
No relationship just a happy customer.
|Thread: Can't get the hang of HSS!|
The tool on the right is too sharp and pointed for brass.
I would use a round nose, maybe 1/2 mm radius with zero rake on the top and left side and about 10 degrees on the front.
I do agree that in the second picture it looks like a very fine thread !
|Thread: Tool post height|
I agree with the comments that Tangential lathe tools are quite easy to male and use. I made one quite a while ago.
Easy to set up and easy to sharpen. You get a good finish too.
This is a drawing of one that I made. Just scale to suit whatever HSS or carbide you want to use.
As you can see the finish is not too bad.
Certainly better than my photography
|Thread: Power feeds for Chinese mills|
I made mine using a car window screen wiper motor. They just don't stop, at all ! They are amazingly powerful.
I actually twisted the centre out of the primary gear on mine by forgetting that I had locked the table. Fortunately I had a spare gear.
I drive mine from a 3 amp 30 volt variable voltage power supply. Usually at about 7 volts. But I have put the full 30 volts on the motor several times for rapid feed without any issue.
|Thread: Tool post height|
Just in case there are those that don't know what the "Norman" patent tool post looks like. This is the one that I made and use. The tool slot will hold a 1/2" inch tool and the height is adjusted by altering the silver M6 cap screw that bears on the surface below. The tool holder is secured by a spilt cotter using an M6 thread. It takes about a quarter of a turn on the cotter screw to go from locked to loose.
Drawings for the Myford size one are in my album !
Its nothing to do with how much you tighten a QCTP ! The problem is with the amount of overhang some have. The tool needs to be within the footprint of the cross slide for maximum rigidity.
I'm not an advocate for QCTP at all having used one and got rid of it in favour of the "Norman" patent tool post and holder. I can use 1/2" inch tools without a problem ! I don't need shims and can set tool height in a fraction of the time it takes to set a new tool using a QCTP. Particularly since I predominantly use HSS tools.
Myford also used the "Norman" patent tool post in the earlier days as did RR in their workshops. I've still got the original Myford four way but its in a box and not used any more.
I do agree about the loss of rigidity with a QCTP particularly the extra overhang that it has.
|Thread: Split cotters|
Yes I agree ! I misread your post then couldn't edit mine. I do apologise.
No it doesn't prevent rotary motion, nor linear motion until the two halves are pulled together. As long as there is a few thou of gap between the halves when tightened they will firmly clamp whatever they are pressed against.
As far as a diameter for the cotter is concerned a larger area for the clamping surface simply means that the force required to lock a shaft is less than a small area.
This is 14 mm diameter cotter intended to secure the block to a 35 mm diameter post using an M6 screw. That gap is just under 2 mm.
Good Morning Guys,
I understand both points of view !
Only if one side of the cotter is longer than the other could there be any possibility of wedging, this could happen if the cotter were cut off centre or the cotter was a very loose fit.
Since a cut in the centre of the cotter would remove material and make both halves shorter by equal amounts the very fine taper on each would be removed.
Any burr on the cut edges will dig into the shaft being clamped and cause sticking and shaft damage so it must be removed.
I agree that the cotter provides a linear clamping action rather than a wedging one ! However as shown in the diagram that Michael posted the red arrows showing the force direction that will be directed at the back of the bore that the cotter slides in.
Quite right, my error !
Since it wont let me edit my original post, error corrected.
I do understand where you are going Martin, but the cotter wont work if there is no gap between the halves. So the risk of any locking is non existent. As far a CAD package is concerned, I use Qcad. The community edition is free but a perpetual licence is only £30.
|Thread: dirty clutch trick|
Hi Brian, Guys,
I've not heard any horror stories about Myford clutches, but slipping a belt is a useful trick ! I deliberately run mine a little loose.
|Thread: Split cotters|
Michael is right, facing off the inside ends would only tend to reduce or remove the burrs that the saw or parting blade left. FWIW I just use the bandsaw to cut the collet across its centre. This usually leaves a 30 thou gap in the middle. Occasionally I face the inner ends if the cut is a bit rough.
? How about considering a split collet clamping a square cross section !
The clamping angle varies very little for a given collet diameter and ultimately depends upon the diameter of the clamped part.
This drawing of a 12 mm cotter with an M6 clamping screw shows the angles for a 20 mm diameter and a 50 mm diameter shaft. The blue lines representing the collet, whilst the red lines the diameter of the clamped item. There is barely 7 degrees between them. A larger collet diameter will only make a small difference. Hardly a locking taper.
As I mentioned earlier the sharp edge on the scallop edge will cause binding and should be removed. I few swipes with a stone is enough.
Hi Derek, Guys,
Whilst the formula are basically correct I just add a couple of MM to the clamp screw diameter. However one thing that you do need to be aware of in cast iron. Split collets exert a great deal of pressure and whilst very effective at clamping that pressure has to be contained. So take very great care that the wall thickness directly opposite to the split collet is adequate to contain the pressure.
In Steel it isn't a problem, but I've seen castings broken by excessive tightening of a spilt collet ! One way round this is to use a small/smaller diameter material for the collet. Virtually all mine are in steel, I've only one in cast iron and one in aluminium.
Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!
You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.
Click THIS LINK for full contact details.
For subscription issues please see THIS LINK.