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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: Nuts
04/12/2019 14:58:36

Steve, no idea but I hope there was insurance and happy to not get involved. This was not in the UK and probably not UK drivers. The item was being transported from ship to site and weighed over 35 tonnes plus the vehicle which is why it didn't stop when the collision occurred.

Martin C

04/12/2019 13:24:47

If there is a likelihood of the stud not being normal to the face of the metal being bolted over it then the nut may have a skewed load on it. This may require spherical washer and seat set underneath the nut to even the loads on the thread or alternatively a longer nut which is likely to be a cheaper option.

Martin C

04/12/2019 12:58:30

Moved bridge span. The flimsy bits were ripped off and the major part of the load and the vehicle passed under the bridge before stopping.

Martin C

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Edited By Martin Connelly on 04/12/2019 13:16:50

04/12/2019 10:04:00

Ega, the answer is that the whole bridge will move as that is what the bull bar is connected to. This is based on an event when the company I worked for had a large load on a trailer travelling on a motorway that hit a concrete bridge far more substantial than this one. The bridge span moved about 300mm. I have photos somewhere and will see if I can find one showing this movement if you want.

Martin C

Thread: Aircraft General Discussion
03/12/2019 21:50:48

On the F4 as well as the initial main gun cartridge there is a second cartridge that is triggered after the seat has travelled half way out of the cockpit. The idea was to keep g forces below a dangerous level by not putting out the full force needed for ejection in one go.These two cartridges put enough pressure into the seat tube to push the seat and crew member out of the cockpit at a high G force so is not just a few psi. Once the seat has risen far enough the tube that is part of the aircraft and the seat part company and this pressure is released with a sound like a piece of artillery being fired. If you look at pictures of aircraft where the seat has been used you can see the tube protruding from the cockpit. The rocket only fired after the seat had left the cockpit.

Martin C

Thread: Another - What is the correct name for this
03/12/2019 19:33:18

Step blocks give a similar result and are designed for supporting items for machining, not sure I would rely on a friction joint to hold up under clamping and milling forces

Arc Eurotrade sell a set that may suit your needs but there are lots of other suppliers as well,

Martin C

 

Edited By Martin Connelly on 03/12/2019 19:38:24

Thread: Meddings M10 VFD?
02/12/2019 15:21:29

Have you been running it off the mains with the current 3 phase motor? If so then the star point may not be required.

Martin C

Thread: Any users of the 'ModelEngineersUtilities here?
02/12/2019 15:17:30

Downloaded in Windows 10

Ran it and had an error

Ran it as administrator and unpacked ok to C:\program files\model engineers utilities

Ran the .exe file with no problems all looks ok.

Martin C

Thread: Screwcutting on the lathe
01/12/2019 21:36:48

Old Mart, I have insert threading bits and insert holders and ground HSS bits tools as well as turning inserts and special threading tools. For the job in the picture the 60 degree insert had enough back rake to cut the thread required. I use what works for the job to be done.

Martin C

Thread: Aircraft General Discussion
01/12/2019 21:26:27

I was near an RAF runway when the crew banged out of an F4 as it was landing, I was at Wideawake airfield when an F4 did a flight test after an engine change. We knew there was going to be a sonic bang.

Martin C

Thread: Screwcutting on the lathe
01/12/2019 18:11:01

The insert in the picture has a 0.2mm radius which I think gives 0.2mm difference from a sharp point.

Martin C

01/12/2019 17:52:29

Sounds like you have the correct setting for 29 degrees. The other issue will be spring in the bar. It is usual to need a number of spring passes with the tool. If you keep all settings the same and do more final passes is the tool still touching the bar or removing material? For long threading jobs a moving steady is useful.

Martin C

steady threading.jpg

01/12/2019 17:35:16

With the tool set over to 29 degrees be sure you are at 29 and not 90-29=61 degrees. If you have your cross slide parallel to the bed as is normal setting this is 90 degrees. Putting both cross slide and top slide screws in line with each other is 0 degrees. It's an easy mistake if you have not cut threads before as many will confess to (myself included). It is easier to leave the cross slide in its normal position and then advance the cross slide half of the top slide movement for each cut. For example if you move the tool 0.5mm into the material move the top slide 0.25mm towards the chuck. This is as good as needs to be to approximate 29 degrees.

Martin C

Thread: Aircraft General Discussion
01/12/2019 17:26:00

From experience I can state that sonic booms and ejection seats going off sound very similar.

Martin C

Thread: Drill Query
30/11/2019 21:27:03

Farnell sell electrical and electronic parts and tooling. This looks like a pcb drilling machine.

Martin C

Thread: New Mill - Starter Tooling
29/11/2019 09:33:36

R8 collets are single size, ER are parallel closing so can be used for a small range of sizes. This means that for a full range of sizes more R8 collets are required than ER collets. Having said that having both ER and R8 gives more options for tool holding. I have R8 in metric (1-18mm in 1mm steps), common imperial sizes and also Morse taper and an ER32 chuck on a 16mm shank. Normally I use the ER32 mounted in the 16mm R8 collet, this gives me two benefits.

1. On my round column mill I can use the ER chucks but if I need more headroom I can take the ER chuck out and use R8 to hold longer tooling or to work in pieces with a large range of working heights. For short tooling I can loosen the R8 and lower the ER chuck all without the need to move the head height.

2. There is no spindle lock on my machine. With the ER chuck I have the correct wrench for the ER nut and the chuck has flats for a large spanner (if you buy one make sure it has this feature if you want it, not all do). This makes it easier to change tooling than loosening and tightening the R8 drawbar.

Martin C

Thread: Back saw for cutting steel and brass?
27/11/2019 12:39:22

Jigsaw blades cut on the pull stroke. It should be an easy task to make a handle for them. If you cant find zero set then rub them on a stone to make them flat and the thickness you want. A cheap option to try if you can't find exactly what you want.

Martin C

Thread: Inside chuck jaws
27/11/2019 10:42:19

Robin, if you make some then record the process for Neil, he wants a short article. Mine have 1/8" hardened and ground pins bought online. They are pitched at 1/4" and the starting position on the jaws is offset by 1/12" (third of scroll pitch). After driving the pins in to the tight fit holes they were ground back to the correct length to clear the bottom of the scroll groove (slightly over 1/8" protrusion). A metric chuck would probably be similar but with 3mm and 6mm for pins and pitch.

My 3 jaw chuck has a set of conventional jaws and a set of reverse jaws. These soft ones are for situations where neither of the standard sets allow easy work holding.

Martin C

Thread: diy power on mill
26/11/2019 13:59:48

It may need to be started at the low setting to restrict starting current. 12.5A is correct if the motor is outputting 150W but this should not be the case if the motor is unloaded.

Martin C

The current draw from the mains for 400W should be 400/220=1.81A plus a bit more for the electronics in the box so 2.2A rating is probably reasonable. 2.2 x 220 = 484W.

Martin C

Edited By Martin Connelly on 26/11/2019 14:03:53

Thread: Inside chuck jaws
26/11/2019 13:33:34

As Clive says scroll to chuck jaw contact is a single point. Since this is the case I knocked up a spare set of soft jaws for one of my chucks using case hardened dowels. They are for thin parts often in aluminium alloy or brass so don't need great force to hold for turning. The jaws are reversible as well.

Martin C

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