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Member postings for Martin Connelly

Here is a list of all the postings Martin Connelly has made in our forums. Click on a thread name to jump to the thread.

Thread: Controlled release of a Clarke Bottle Jack fitted to an engine building stand
06/01/2022 14:11:39


06/01/2022 13:08:32

A small clamp-on bracket on the left hand plate, a pivoting nut on that bracket, a clamp-on lever on the release valve with a pivoting anchor point at the top and a screw with knob between to two pivots and you have a controlled release mechanism for very little cost or effort.

Martin C

Thread: Drill mill X and Y backlash
05/01/2022 21:37:33

2.5mm pitch trapezoidal is not listed in my Machinery's Handbook but the formulae for calculating the depth and other features based on the pitch are shown. Using these should give enough information to form the 2.5mm pitch correctly.

Martin C

Thread: Controlled release of a Clarke Bottle Jack fitted to an engine building stand
05/01/2022 13:25:43

You could add a lever to the release valve and then operate the lever with a screw to give both control and limited movement to the release valve. I don't know what your setup is like but this type of operation would allow you to put the release operating knob in a convenient position and also avoid accidental release caused by catching the release valve operating knob.

Martin C

Thread: UK source for 17/32" ring spanner ?
04/01/2022 15:42:09

Google special spanners for English cars and motorbikes 17/32" .

Martin C

Thread: Machine a rectangle from a bar
03/01/2022 10:56:30

This is based on a standard milling vice, the horizontal bar should be shorter than the face it is on to avoid marring machined corners. If you clamp the machined face to the fixed face of the vice ( as John suggested) you can then put a horizontal round bar or even a ball bearing between the moving jaw and the workpiece (not in a vee if the jaws have them, it needs to be able to roll) to ensure it is as flat as possible against the fixed jaw. this will get two of the faces at 90° to each other. Check this is giving a good result before continuing. Then repeat, keeping the first face against the fixed jaw and use a square or 123 block on the base of the vice against the second machined face. This should give 3 faces that are perpendicular to each other. Once you have done that you can use either the base of the vice or a parallel in the vice to machine two more faces. The last face do not use the round bar or ball bearing on the already machined faces as it will mark them but at this stage you should be able to hold the part supported on two parallels or the base of the vice and tap it down with a machinists hammer/mallet/suitable heavy lump before machining. Providing your mill and vice is set up well this should give a good rectangular block to work with.

Martin C

Thread: Headstock - Performance of the gears
02/01/2022 17:50:19
Thread: Chuck jaw help
02/01/2022 11:01:12

This page refers to Indexa 3500 jaws. Zoro chuck jaws

In May 2020 I offered a set of these jaws free to anyone who needed them (as opposed to just wanting them) Outside jaws for Indexa chuck 

If they will fit your chuck you can have them for the price of the post and packaging. The dimensions are shown apart from the pitch of the scroll which is 7mm. They are for the 125mm chuck but, from the given dimensions, if the scroll pitch is the same they should fit.

Martin C

Edited By Martin Connelly on 02/01/2022 11:25:09

01/01/2022 17:36:23

Once you have machined soft jaws at one point moving them to any other position tells you only one thing, they were not machined at that point and there is some runout that may be due to the jaws or may be due to the scroll or may be due to the chuck. In other words it tells you nothing of use.

Martin C

01/01/2022 12:31:09

How does truing up soft jaws tell you what the run out is? The point of truing up soft jaws is that it eliminates problems of run out.

Martin C

01/01/2022 10:56:18

These people also sell various chuck jaws. Since they have dimensioned drawings for some of them this may help identify what you have.

Zoro Uk

Martin C

Thread: How do you find someones 'profile'?
31/12/2021 13:47:52

Go to his album and then click on his name JohnF, brings up his profile.

Martin C

Thread: Middle of Lidl
31/12/2021 12:38:47


Thread: What tool do I need? I need to measure the radius of a tiny fillet on a 90 edge.
31/12/2021 09:45:23

I have a micrometer barrel that was saved from a tool that was being scrapped, like a depth gauge without the foot. I would make a tool that held it at 45° to the edge and could be adjusted to read zero on a sharp corner. Then anything less sharp can be measured and the reading converted to a reasonable idea of the radius with simple geometry. You may also decide that a simple 45° chamfer is all that is required. It would certainly be good enough to decide what was a good value to go for. Imagine the centre finding slide of a combination set with a micrometer barrel instead of a sliding rule.

Martin C

Thread: Maths problem just for fun
31/12/2021 00:51:58

Greensands, this is from my post on 17 Dec. The quartic equation I came up with and which I used my old calculator to solve for the ladder against the wall.


Martin C

30/12/2021 14:42:38

We installed an RO (reverse osmosis) system at work to demineralise (as opposed to de-ionise) water for pressure testing stainless steel pipes. You can get small RO systems for filling and topping up aquariums where you only want to replace the water that is evaporating from the tank. I guess one of these would do for boiler water.

Martin C

Thread: DAB radio
30/12/2021 12:12:22

I always have the local radio online transmission/internet delivery through the computer when I am using it.

When DAB first came out one appeared in one of the offices at work. The reason was that it was no good in the owner's house. It was a bit so-so in an office inside a metal box type factory building but did work in just one location in the office. As a result I have never bought one and I have not heard anyone say recently that FM is going to be shut down soon like the first propaganda regarding DAB claimed.

Martin C

Thread: BBC Micro Boxford TCL125
29/12/2021 12:56:47


Martin C

Thread: Sieg SC3 With DRO fitted - Cross Slide Lead screw - Metric or Imperial
29/12/2021 12:51:06

You have a DRO. Measure the cross slide movement you get with ten turns of the handwheel and divide the result by ten. You will find the pitch of the leadscrew. Ten turns gives a better average than one turn if there is any wear. It should be clear from the pitch if it is metric or inch based.

The presence of a DRO makes me think that backlash will not be much of a problem. You are usually pushing a cutting tool into a workpiece on a lathe so backlash does not cause the same sort of problems on a lathe that it causes on mills and a DRO on a mill is usually good enough to take care of the backlash issues.

Martin C

Thread: Converting a bench top mill to cnc.
29/12/2021 12:40:35

If you are using CNC doesn't that make the DROs redundant? I think in theory you could have a closed loop CNC that uses DRO feedback but it would be more bother than it is worth to set up since it is usually possible to put backlash figures into CNC controllers and in some cases screw mapping.

If you want absolute positioning then the use of a homing setup will enable that.

I think there was some discussion, that may have been in this forum, regarding the output from DROs and it gets quite complex very rapidly as most systems are not interchangeable as they use different protocols.

I have not had any issues with stepper motors and DROs on the same machine but as I pointed out above there are many different systems so there is no 100% guarantee there will be no interference issues.

If you are thinking that you want to use the machine in both manual and CNC modes then consider the fact that a cheap mini wireless USB keyboard can be used to operate a CNC machine. This means you do not have to keep going to the CNC computer to move an axis and so can effectively work like a manually operated machine.

Martin C

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