Member postings for Martin Cargill

I have a pair of toolmakers clamps made when I was an apprentice 45 years ago. They are still working well (touch wood). The clamps were made from scrap shanks for lathe tools. Our factory must have gone through a fair amount of tooling as they managed to provide our apprentice training school with around 200 pieces of steel a year.

The origin of the steel made it difficult to drill and tap because it was harder than the mild steel that we had used for our previous tool making projects - a few drills were blunted and a few more taps were broken during the manufacturing process.

I had a similar, but not the same problem, with my Arboga pillar drill. I don't have three phase power and the motor was two speed, three phase. The two speed motor made fitting an invertor drive difficult. I decided to fit a single phase motor but discovered that the existing motor has a shaft about a foot long with a gear machined on the end.

Problem was solved by swapping the existing motor fan for a pulley and then adding a single phase motor to drive the pulley. The new single phase motor now drives the machine using the old motor as a kind of layshaft.

I got the idea from work where we used a similar trick to drive oil pumps with failed bespoke motors with replacement standard motors.

You could possibly do the same but use an invertor powered three phase motor to drive your single phase motor.

Martin

How high off the ground is the lifting point? Most engine cranes do not have the height to lift a mill onto a trailer. I have a two tonne crane and it took a bit of mucking about to get the slinging and lift chain on the crane short enough to allow us to lift a Viceroy lathe onto a trailer (pushing the trailer under the crane once the lathe was lifted). Remember to hitch the trailer up before loading it.

Be careful as well because stripping bits of the mill to reduce the weight will change the centre of gravity and you may end up with the lifting point not being at the correct point for the lift being made.

Martin

Thank you for all of your comments. The snapped section of the electrode is about 150mm long. There is another section (that I have cut and used to make a temporary repair) that is about 600mm long, This part is not heated so I have made a temporary repair using copper wire, but I want to make a permanent repair using the correct material.

I have talked to the manufacturer of the machine but they are not being very helpful as the gas portion of the machine would have been sub contracted when the machine was made.

I am aware that there are safety implications but the gas side is controlled by a safety relay with ionisation detection (another similar electrode) and if it does not detect a flame within a couple of seconds it shuts the whole machine down.

I do have a relative who is a gas engineer so I will talk to him to see if he can enlighten me any further as to possible solutions.

Martin

I look after a couple of barrel charring machines - used in the cooperage industry. One of the machines recently broke its ignition electrode rod. Its a 3mm diameter rod that sparks to earth to ignite the gas flame. Because its in the gas flame it gets heated to a cherry red about every three minutes. Anyone have any idea what material it will be made from so that I can try and find a replacement?

The non heated end has a thread cut into it to accept the top from a spark plug, does anyone know what thread is used on the top of a spark plug?

Thanks in advance

Martin

Edited By Martin Cargill on 04/09/2023 20:19:44

Mark.

I hadn't thought of it in those terms, I think you're right, I was misled by some articles that I found where the blade cross section was taken into account during the calculations. This explains the markings on the Lenox gauges.

Martin

Thank you all for your input. It looks like I'm going to do some calculations to work out blade tensions.

One thing I can't work out is that the videos and photos of the Lenox gauges show them with yellow/green/red segments on the gauge face - surely the tension must change with the dimensions of the blade, yet their gauge does not allow for this, unless they have specific gauges for specific blade sizes?

Martin

I already have a blade tension gauge. It could probably be described as a "stretchometer". But the blade stretch varies depending on the width and depth of the blade. To avoid having to do a calculation for each blade size I was looking for a table covering the standard blade sizes, perhaps such an animal soes not exist.

Martin

Brian. Thanks for your input, I have used a similar method in the past but I deal with a range of machines using blades from 1/4" to 6" wide,on this range of sizes trying to achieve the right tension by ear is difficult.

Martin

Has anyone come across a blade tension guide? I have a blade tension gauge for bandsaws. It works by measuring how much stretch the tensioning system puts on a blade. To then work out how much tension is being put onto the blade you then need to make a calculation based on the cross sectional area of the blade.

Surely someone must have compiled a chart that shows all of the common sizes of blades and their relative elongations to ensure correct tensions.

I know that some machines (especially wood machines) simply state to apply as much tension as is required to cut a straight line, but, with metalworking machines this is more difficult to achieve.

There must be a chart somewhere but I cant find one.

Martin

I used to work for a company who sold and serviced/repaired bigger metal cutting bandsaws than the one in question. One check we used to do to see if the blade was trying to push its way up onto the shoulder of the wheels was to trap a piece of paper between the blade and the wheel as the saw was running. If the paper was cut between the back of the blade and the wheel flange then it was out of alignment.

Obviously you have to run the machine with the blade cover open to do this so please be very careful how you do this to make sure you don't get your fingers in the wrong place !!!!

It will have a relief valve (to prevent overloading) these are normally a ball bearing pushed by a spring. They are often under a plug marked "do not touch" or similar. Take the plug out and remove the spring and ball. Clean the seat and the ball, then use a punch and reseat the ball with a sharp tap. Reassemble and test again.

Has the machine got adjustable feet - or holes that can accommodate feet? Use the feet to lift it off the pallets - some cutting of the pallets may be required.

Or just set fire to the pallets

The motor on my lathe is supposed to use a current sensing relay that disconnects the start winding once the start current drops off. when I got the motor (second hand) the relay was missing and a replacement was not to be found (the original relay was an American device). I have mine wired with a second set of contacts wired to the go pushbutton, pushing the button brings in the contactor for the main winding and powers the start winding. You simply hold the button in for a second or so until the start winding is no longer required and then release it.

I got the idea of operating it like this when came across an identical set up on a single phase Sedgwick saw bench with a 4hp motor, although in this case the run up time was about 10 seconds and a label instructed you to hold in the button until the saw reached full speed.

Martin

One of the points I was making is that even though the MCB for this particular circuit had tripped, The RCD, because the neutral network will allow current to flow to earth from other live circuits, will still trip.

Its one of the problems with RCD circuits - you can isolate any circuit to work on it but inadvertently touching the neutral of the isolated circuit to earth will trip the RCD and will plunge the whole house into darkness.

I think there are too many people on here trying to (wrongly) explain how an RCD works. it is nothing to do with neutral to earth voltages .To put it simply an RCD compares the current flowing in the live conductor with the current flowing in the neutral conductor. If they are not the same then there is current flowing through another route. This route is to earth. Household RCD devices are set to trip when the current comparison exceeds 30 mA of a difference.

A single RCD in a distribution board usually protects a number of circuits in the house/workshop so, because the neutral wiring is all joined together at the distribution board then earthing any one of the neutral wires anywhere in the house (even on a circuit that has its live feed isolated) will cause current to flow to earth from any of the other live circuits, thus causing the RCD to trip.

Martin

FASH

This reminded me of the Scottish radio wind ups. Hector Brocklebank of HB Fash - Google it

Martin

Just a thought when checking for motor faults.

Checking resistance values on a motor are no guarantee to find a short circuit. A short between adjacent turns will produce resistance values very similar to the overall resistance figure but a shorted turn will draw huge current when its energised.

If the fault is across a large part of the winding then it may show up by measuring resistance.

Martin

Steampunkedd,

I have a small QCTP that I bought for my Boxford but its too small. It is a simple clamp type and has two tool holders but its not a difficult design to copy to make more. Give me a shout if your interested and I can give you some sizes to see if it would fit your machine.

Martin

I have a Tiplap grinder. These machines are (or so I thought) just for dressing lathe tools. I have modified mine by mounting the motor further back and making square and hexagonal blocks housing a MT3 sleeve inside to allow me to hold and grind mills and drills. The MT3 sleeve also allows me to hold a drill chuck and my ER32 chuck to hold parallel shank tooling up to 20mm thus allowing me to sharpen most of my tooling.

Browsing the web today (because I have Covid and I'm bored) I found some pictures of the same grinding machines but they were being used for dressing the end of milling cutters using a simple indexing pin/disc setup. This setup uses the hole through the head of the machine to hold a simple spindle/chuck arrangement.

I would like to make something similar for my machine but before I do does anyone have a Tiplap with this same feature. I can obviously simply design and build one myself from scratch, but its got to be worth looking at what the manufacturer built first.

One of the tools I would like to be able to sharpen is a seven flute Rotabroach cutter and an indexing disc would make this possible.

Martin