Member postings for old mart

You should set the gibs so that the movement is slightly restricted but not tight throughout the full travel. The blocks can be checked against each other sitting on the mill bed, if they are not square you will see a gap when they are one way round. Keep bringing them together and with a decent steel rule or straight edge you can also check the lengths, by using a torch looking for any light showing. I bought a pair of 246 blocks which caused problems until I chanced to see a gap at the top when the bottoms were sitting together on the surface plate. They were reground for free, but now they are square, but slightly different sizes. As they improved for free, I did not say anything and knowing them now I can compensate.

I made a rotary broach some time ago for internal squares and hexagons and engraved the face to tool tip length on the body. This is the null point which is important. Outside rotary broaching is very rare, I had never heard of it before this forum. External shapes are usually produced by milling or with a fly press.

As already mentioned, the gibs have some affect and it might be useful to check any differences made when locking the movements. The double testing at 180 degrees should give identical results even if the tramming device is not perfectly straight. With a shorter tramming spindle you could repeat the tests with the head lower.

Edited By old mart on 30/04/2023 16:10:46

I have often wondered if the USB outlets built into wall sockets use any electricity when they not charging.

I bought one of the Lidl cordless rotary tools which is in the Dremel style, the PFBS 12 C5, not so long ago, and also a kit of extra cutters and think it is very good.

I took some more pictures, and the two views of the mechanism show the spindle at the top and also extended. The long keyway which takes the drive from the bevel gear is visible in the second, and the quick helix visible in the first when the spindle decends. The thrust race inside the drill is on the flywheel spindle which has the adjustable tension pad on it just above.

I forgot to add the photo's to the album before posting, bear with me,

Edited By old mart on 27/04/2023 20:31:16

Edited By old mart on 27/04/2023 20:33:06

Edited By old mart on 27/04/2023 20:36:57

I have just looked at the 1980's Crawford catalogue and cannot find any 1801 part number.

The photo also shows part of another number ending in 94.

Edited By old mart on 27/04/2023 17:53:43

Edited By old mart on 27/04/2023 17:54:37

It has the Crawford logo on it. Tightening from the front seems strange as you would have to have a special triangular spanner, and there is the expected slot milled to engage a pin in the spindle bore to stop it turning. I have the Crawford catalogue somewhere on a pc and will look for any info.

No luck on the lathes UK website, but I have found the catalogue on disc, but will have to look at it tomorrow.

Edited By old mart on 26/04/2023 21:37:55

I would think that when you break through and stop winding, the spinning flywheel would withdraw the spindle as it slows down. I must try it out again tomorrow. Also check that the spindle is keyed to the bottom bevel gear with a long slot for drive and axial movement.

We thought that the threads, one of which is a fast helix would work together to provide the downfeed as the spring load adjuster with a bronze tip appears to push against the sleeve with the threads and is what prevents it freewheeling. We have not dismantled the machine to be sure how it works but having comformation of our guesses is helpful. I would not like to drill holes smaller than 1/8" with it. The adjuster applies friction to the flywheel which has the fast helix inside it with the main spindle screwed into it and the spindle is free to decend until the bit hits the work. That explains why the flywheel stays still at first. A rather clever design, not an automatic feed like a lathe has at all. I used to have a Stanley hand drill which had exactly the same design of two gear ratios.

I have Mitutoyos and a Tesa but recently have bought a Dasqua and it is excellent and 1/3 of the price. There are several variations to choose from.

Mike brought in an interesting old hand powered pillar drill today. It is about 2 feet high, with two gear ratios and a variable downfeed. The downfeed puts pressure on the drliibit as you work through an adjustable slipping clutch which we don't really understand. There is a flywheel at the top of the drill which starts turning as the drill bit hits the work, the red adjuster is on the left and on the right, the other red part is a greaser/oiler. The Jacobs chuck is not original, and the spindle nose has been modified to a Jacobs taper to fit it. It was rescued from some scrap in the 80's by Mikes father. Some wording on parts appears to be in German, but the label fitted is from a Bristol company.

Any information would be appreciated.

The one we have looks like that, but I cannot remember the details, at least I do know exactly where to look for it.

You were lucky with the stainless, some grades are not nice to machine.

I have seen double decker busses going over these bridges, I had no idea how heavy they were.

We have a faceplate at the museum, somewhere between 5 and 7 inches diameter with a similar thread in it. I will have a look at it on Wednesday, it was in some donations and might possible be what you are after, it has no use here.

The pitch of threads like these is not often standard nuts and bolts configuration. You might be able to tell the angle with a light and magnifying glass if you have anything with a known 60 degree angle to compare it with.

Yes, if one fell onto the railway line it would certainly make the headlines.

It might be possible to use a 4 or 5mm high tensile screw with a special washer to centralise the insert. A shoulder for the insert about 2mm deep would keep it from moving and the hole for the thread can benifit from being offset about 0.1mm to hold the insert tight. The forces are mostly down into the seating, so the screw is not stressed too much.

The other day on my way to the museum, I was overtaken by 4 fire engines in full panic mode. They must have passed over the railway on bridges which were restricted in weight capacity. Do they have special dispensation to overload bridges?