Member postings for old mart

Can we have a picture of your angel eyes?

I looked at the link, and one think caught my attention, the use of screwjacks on a lathe faceplate. You would have to be very careful in that application, to allow for centripetal forces, of risk getting a nasty surprise.

I hope you get to see the result of the piano restorers work when he is finished, your special screws will still be in use in a hundred years time probably.

The best way to get up and running with threading is a bit of brass stock, say 25mm diameter by 50mm long. You can do test cuts, and then turn down to fresh metal. I usually do threading by zeroing when the tool touches and then cutting down to the thread depth using the charts. If you have the nut which is to be used, or mating part, then stop cutting very slightly before the theoretical size and use the nut as a gauge for a perfect fit.

Its nice to have a small supply of these jacks, they don't get much use, but when they are required, they are worth their weight in gold. We have a selection from about 5/8" starting height to 4", I have only needed them once. The long threaded couplings included in the tee nut clamping sets have potential for dual applications.

Three phase motors for small applications have up to 8 poles, the more poles, the slower the running, so with equal horsepower, the torque increases the slower the motor runs natively. The motor I bought has 6 poles, the 8 pole one was 50% more expensive.

This is the one I bought:**LINK**

I wouldn't trust any tap or die advertised as "tungsten steel", it is there to impress the ignorant.

It just shows that a bit of positive thinking can overcome all obstacles, well done.

Your depth of cut should start at about 0.1mm, 0.004" for about three passes, and then reduce gradually to 0.025mm, 0.001" for the finish cuts. A good guide to the depth of thread to cut are the tables that I normally use from Motalia. For your 10 X 1.5 mm, the depth is 0.92mm, 0.0362".

**LINK**

Another factor is the rated rpm of the motors. I have changed a 1425 rpm single phase to a 935 rpm three phase one, as the minimum lower speeds available would have been too high for larger drills and cutters. With the vfd set as I want it, the three phase motor will reach nearly 1400 rpm and go down to 467 rpm, which in conjunction with the four belt positions gives a better overall spread of power and speed. Remember, that a three phase motor on a VFD running at 25Hz is not only half the speed, but also half the power, and the power drops rapidly if the frequency is lowered further.

We used to stress relieve steel at 190C for a couple of hours and then cool naturally. This is in domestic oven territory. It might work on cold rolled mild steel. We just made 11 10mm threaded  tee nuts for 1/2" wide slots from a 300mm length of key steel and didn't notice any bowing.

Edited By old mart on 16/11/2019 18:46:35

Edited By old mart on 16/11/2019 18:48:05

I have taken some pictures of the rotary broach I made. The bearings are a double row deep groove and a thrust bearing, the er25 collet works for different size cutters. The number etched on the side is the length the cutters must project to have their tips at the null point. I made cutters for square and hexagonal holes.

At the museum today, I destroyed all the grinding and cutoff discs which were out of date, including my own which were the oldest. All that are left are about 8 Dewalt cutoff discs which have 2021 on them. My little 76mm discs for the 12V Parkside angle grinder have a date of 2022. I also have some Parkside 76mm general purpose carbide edged metal discs which also have the 2022 date on them, despite having an indefinite lifespan.

Diamond discs work for metal, but aluminium may clog them, and steel and cast iron will reduce their life as ferrous metals have an affinity for carbon, which means the diamonds dissolve in the iron when they get hot.

Edited By old mart on 16/11/2019 17:38:57

Have you looked on the Lathes UK website? They also have manuals and parts lists.

I looked at lots of adverts for angle grinder discs, and not one seller was admitting to the date of expiry.

You must post photos as you go. It looks like it will be a nice machine when it is finished.

That is a similar reasoning that I came up with when I decided to increase the spindle of the Tom Senior mill from MT2 to R8. The bottom bearing is increased from 1" bore to 35mm bore.

There are several ready made small mill lower parts which have the X and Y axes on the market which are potentially very useful when making a mill. I found this one, but there are larger ones about.

**LINK**

Here are some pictures of the two halves of the spindle which was bonded with Loctite 620. No pins were needed as the halves also screwed together.

Edited By old mart on 15/11/2019 16:43:44

I replaced the thrust bearings with metric ones, they were slightly greater od, so the housing bores had to be enlarged. The new bearings are heavier duty.

I'm not at all sure, but isn't rubber a product originating in South America? And what we now call rubber bands could not have predated Goodyear's invention of vulcanising.

That's why I asked, having never thought about that subject before. I can destroy the entire stock of out of date discs now to prevent an accident and the bad publicity that would ensue.