Member postings for John Purdy

Please disregard the above post! The schematic is right, I wasn't thinking straight!

If a moderator sees fit you can delete this and the above post. Thanks.

John

I have been following Carl Wilson's article in ME on an "Electronic Hipp Toggle Circuit" with the idea of using it with some modifications. I plan on using Hall effect devices vice opto interrupters. This will require some changes to the logic as the output of the Hall devices is high in the unenergized state whereas the opto ones are low but I haven't decided how I will implement it yet.
In going through the schematic, the block diagram and description of the logic flow, unless I am misinterpreting something, it seems to me there is are some errors in the schematic as drawn as it doesn't agree with the block diagram and the logic description.

The way the schematic is drawn the outputs of the three flip flops appear to be backwards. The output of the "MIN" F/F is shown as the "Q" output but the block dia. and description both show it as the "NOT Q" output. Same for the ENA and ON F/Fs both shown as "NOT Q" where a the block dia. and description show both as the "Q" output. (The ON F/F does show the output labeled as "Q" but is in the position of the "NOT Q" output )

The description and the block diagram appear to agree.

John

Edited By John Purdy on 31/10/2022 02:50:23

Edited By John Purdy on 31/10/2022 02:54:39

When I bought the 6" vice for my mill, 40 years ago, it weighed 75 lbs. Over the years it has inexplicably gained weight, it must weigh at least half as much again now! I has become harder and harder to move it from the mill table to the bench and back when I need to work directly on the table. Not to mention the safety aspect. A couple of weeks ago I developed a case of gout in the middle finger of my left hand, the vice was on the bench and I needed it on the mill. There was no way I was going to be able to move it with my disabled finger so something had to be done. My solution was a piece of 1" board 5"wide of sufficient length to reach from the mill to the bench with a tongue screwed and glued on to the end to fit in the slot in the mill table. I glued a piece of scrap "arborite" to the top to give a smooth sliding surface. The "arborite" came from somewhere, one of those things that are too good to refuse " has to come in useful one day"!
In use the knee is lowered to the bottom, and the board is put in position from the mill to the bench, the tongue in the slot keeping it in position.

The vice is then slipped up onto the board.

Slide down and turned around.

Then tipped up onto the bench.

Putting it back on the mill is just the reverse, tip it up onto the board slide it up, turn it around and slide it over onto the mill table. No more heavy lifting or risk of dropping it on my foot!

John

Edited By John Purdy on 10/10/2022 20:07:07

Jason
I think the gears were purpose made (and not very well IMHO ) for the Sanderson either by or for Clarkson's as the bores and hubs required no modification other than drilling and tapping the mitre gears for set screws. As can be seen in the pic below the teeth are not of involute form but are triangular. The top two are the ones where the teeth are cut at an angle to the radial line of the blank. It is most obvious in the top left hand one at about 1 o'clock.

I did try different positions of the pinion relative to the face of the gear to see if if they would mesh better for as you say the effective DP (or more accurately the tooth spacing ) changes from inner to outer edge of both the pinion and the gear. I found if I moved the pinion further out as in the this second pic they rotate fairly well but still roughly. If I have the pinion in what would be the normal position with the two faces matching they lock solid and won't rotate at all. I think I might try your suggestion and mount the crank shaft between centres, so it can rotate freely , on the dividing head on the mill and with the pinion held in the spindle, lap them together while slowly increasing the engagement to see if I can get them to run smoother.

John

Actually, Michael, I had seriously thought of doing that, but after doing the calculations I think that they are too far out for that to be a viable solution. I have done that before to get pairs of gears to run smoother but they have all been the same DP only had some rough edges that the lapping took off.

John

Edited By John Purdy on 08/10/2022 01:21:31

I've finally finished my Sanderson beam engine except for the governor drive and governor and have run into a couple of problems. When I bought the castings, I also got the 6 gears from Clarkson's. I didn't check them closely on receipt but now I have found the the teeth on one pair of the mitre gears are cut at an angle to the gear centre line, hence when meshed the shafts are at 90 deg in one plane but are out by about 15 degrees from 90 in the orthogonal plane. Now on setting up the 3:1 drive I find the pinion and bevel gear don't mesh properly. It's as if the two are of different pitches and as they rotate instead of the next tooth falling into the next gap smoothly it is hitting the tooth either side of the gap and jumping into the gap. So I calculated the theoretical pitch circle diameter (PCD ), and OD for both pinion and gear of a 3:1 set 32 DP with 12 and 36 teeth and find that the pinion appears to be right but the gear is too small. Working back from the OD and PCD of the actual gear it works out as about 33.5 DP, which would explain why the teeth don't line up when rotated together. If someone has a set of gears as currently supplied by Blackgates could they measure the OD of the 36 tooth gear and let me know what it is. My calculated OD is 1.14476" and the OD of my gear is only 1.100".
Also on a different note the governor on the original Clarkson's drawings is only an outline with a couple of dimensions on the main shaft, also my drawings have been left out in bright light too long and in that area are barely legible. If anyone has the current Blackgates drawings are all the parts of the governor detailed? If so I will have to consider getting them or engineer the unit from scratch. Thanks.

John

Robin

Like Ramon and Martin I make my own as the need arises. The largest in the pic is 7/8" and the smallest is 1/8". The three largest are expanded by a tapered plug and the five smallest are just drilled and tapped with a taper tap and expanded with a normal set screw. ( The 1/8' one has a 1/4" one on the other end ). The slits are made with a slitting saw, four for the larger ones and two for the smaller. (On occasion If I'm in a hurry I have just used a junior hacksaw! ). In use I chuck them in the 3 jaw "Griptru" chuck ( a 4 jaw would work just as well ), clamp the part onto the mandrel by tightening the screw, then, with a DTI on the outside of the part, adjust the chuck till it runs true. For non circular parts I just adjust the mandrel itself to run true.

John

Old Mart
If your level is a M&W #305/6 (the same as mine ) according to my old James Neill (M&W) catalogue the sensitivity is quoted as "2 minutes - Bubble movement of one division (2.5mm/ 1/10 in. )indicates an off level of 0.18mm per 300mm or .007in. per foot". The sensitivity of the 8,12 and 18in. versions is listed as 1/2 of the above.
John

I've now gone through the paper indexes for both ME and MEW for the 80's and 90's with no luck. So perhaps it was the one in the Oct 1976 ME that Tony mentioned that I am thinking about. Will have to check in the club library next time I'm down in Victoria, whenever that will be, it's a 498 km round trip.

John

Thanks everyone for your replies so far. The one Tony mentions in ME might be the one I'm thinking of. Mine don't go back quite that far (1979 ) but I may have seen it going through old copies in our club library (they go back to day one ). The one detailed in the Climax article and book is metric and with a bit of math the dims. could easily be modified to be imperial which is what I want as all my gauges are in PSI ( except the one on my German toy steam engine which is in bar! ). Thanks Bill and Duncan for your offers.
Here's the gauge I currently use for boiler testing.

I've had a look through the "Live Steam" mags and he describes a dead weight tester at the end of the Climax series in a section on making a pressure gauge. In those articles he mentions that there will be an imperial version in the forthcoming Heisler book but there is nothing in the Heisler build series in "Live Steam".
Looking at the one in the Climax series the diagrams don't fit with the images I have in my minds eye. Unless someone comes up with something I will have to go through the paper indexes for the 80's and 90's and see if anything pops out at me.

Steven: I've got photo copies of Roy Amesbury's articles on making pressure gauges but on testing , all he says is "Of course the gauge must be checked against a large accurate one".

John

Thanks Baz and Steven but I have never had any of his books so it can't be that I'm remembering. I do have the "Live Steam" mags that have a couple of his construction articles, so will have a look through those , but I don't think that is what I remember.

John

I've been looking for an article on the above subject, which I seem to recall was in Model Engineer, probably in the '80s or '90s. I've gone through all the online indexes using all the search phrases I can think of with no luck. Does any one recall such an article? or am I dreaming (been known to happen! ).

John

Roy

I've sent you a PM.

John

My suggestion to find where the problem lies would be to run the cross slide well out to the front of the lathe then remove the two screws either side of the bracket that holds the feed screw to the cross slide . You should then be able to manually move the cross slide back and forth, right off the saddle to the back if you go far enough. If you can't and it becomes stiff and won't move back then as suggested above the gibs need adjusting. If it moves freely back, then with the cross slide well back and holding the feedscrew bracket in one hand run the feedscrew in till the stop on the screw hits the saddle. If it goes all the way in with no binding then push the cross slide towards the front to meet the feedscrew bracket and reinstall the two screws. That should align the feedscrew with the cross slide and allow for full movement in and out of the of the cross slide. Doing this should tell where problem exists.

John

Here on the west coast of Canada I just received #4695 15 - 28 July in this AMs mail. Haven't received #4694 yet. Got #4693 a number of weeks ago.

John

Edited By John Purdy on 22/07/2022 19:14:32

Jason
I think I know what happened. When I went to add the pics to my post yesterday I couldn't find them in my albums (finger trouble! ) so I re-loaded them into my "Misc." folder so I could add them to my post. A short while later I found the originals in their own folder so I deleted the ones in "Misc." that I had just added, as a result the link from my post to the pics was no longer valid, duh!!! The same thing must have happened to the pics in my previous post. I remember re-organizing the pics in my albums a while back so that's probably why the pics disappeared from my post in 2016. I guess there are probably now a number of my previous post where the pics are no longer visible. Sorry to everyone for the problems this has caused.
John

This is Jason Posting

Not sure of the reason but I'm going to add them as you would have done and see what happens

Jason

Yes I just noticed that. The pics in my post from yesterday have gone and the links give a "Page not Found" error msg. As you say the pics were there for a while yesterday. Any idea what's going on???

John

Jason

I believe Baz was talking about the links that have replaced the pics in my original post here of 06/2016.

John

Edited By John Purdy on 21/07/2022 00:33:41