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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: Surface finish
02/01/2019 21:15:55

Bolts are not often machined from solid. The bar stock is cut off and one end heated then swaged out to form the head. This requires material suitable for this process and it also sets up a variable grain structure in the bolt. As a result bolts do not make good raw material as you are finding out.

Martin C

Thread: what tool is this?
02/01/2019 12:48:42

Could it be missing a tapered part that forces the pins out when the bolt is screwed in?

Martin C

Thread: New Mill - Starter Tooling
02/01/2019 12:46:20

If you milled the 8mm slot past full depth first then it would be possible to make a small single edge cutting tool with a piece of HSS (even an old milling cutter that can be repurposed when at the end of its normal life). Rough out something like Ø14mm x 6mm deep knowing you have an easily sharpenable tool that does not need to be pretty or an exact size then clean up to size with the tee slot cutter.

Martin C

Thread: Small part holding
01/01/2019 11:27:11

Pin chuck or ER11 colletsfor small round parts.

Martin C

Thread: Simple and accurate home "switch"
31/12/2018 10:11:34

I have a repositionable z axis home/limit switch, it clamps on the ways. Having collets, a 4 jaw chuck and two 3 jaw chucks that are all different distances from the headstock makes use of manual data input (mdi) risky if you make a mistake with z axis movements. Also using as a home switch before work comences allows everything to be switched off when I want to stop (always saving fixture settings on exiting Mach3) . Re-homing next time I power everything up means the z axis is set without touching off the workpiece. I also have x axis homing for the same cold start reasons. Since I sometimes have to move the tool post from one tee slot to another calibrated tool holders and tool tables are not much use to me.

Martin C

Thread: Vertex Rotary Table equal 13 sectors
24/12/2018 09:54:40

If you have a 65 tooth gear index using that.

Martin C

Thread: Tungsten Alloy
21/12/2018 14:22:31

Duncan, did this get resolved? Tidying up I've just found a piece of tungsten copper 1/2" x 1" x 4" long that I found in a scrap bin at work some years ago. Kitchen scales say it's about 460g which works out to a density of about 14g/cc. Some shallow grooves on one side and some 3.5 dia holes about 3 deep on the other but plenty of usable material.

Martin C

Thread: How far to be off tool centre before a turned finish becomes poor?
15/12/2018 09:49:54

I set my tool to centre height with a steel rule on the bed and mark one eyeball. Tool height is 4". It is rare that I have no centre hole so I don't generally have centre pips to judge by. Seems to work fine. I believe the trick on larger lathes in industry was to set a tool to the correct height then use it to scribe a line on the tailstock barrel for future use.

Martin C

Thread: Squaring in the lathe
12/12/2018 16:38:31

A small angle plate on a faceplate and a square (or 1 2 3 blocks) should work. Just needs care with balancing everything and making sure nothing can fly off. Remember the cube does not need to be on centre.

Martin C

Thread: Is this Morse shank removable?
10/12/2018 22:39:01

It's possible that a standard chuck arbor has been used. The head could easily be made with a Jacob's taoer and the two parts pressed together. The gap would allow wedges to be used to separate the parts.

Martin C

Thread: DNMG110408 & CNMG090308 Inserts
10/12/2018 17:39:05

Bluntness is the nature of carbide inserts. Don't try taking off very small amounts on diameters with them. They may rub all the way along or they may get under the surface randomly resulting in a rough finish. They need to be taking a reasonable depth of cut such as 0.2mm or more for best rrsults.

Martin C

Thread: Straightening coiled small steam pipe.
09/12/2018 18:49:16

Torsion can straighten wire and soft tube. Plug the ends, solder may work, grip in lathe chuck at one end and tailstock chuck at the other. Use the chuck key to rotate the main chuck manually, should not take much rotation to straighten it.

Martin C

Thread: Some questions about a Collet Chuck
05/12/2018 15:19:45

I have an ER32 and a smaller ER11 (I think) with nominal Ø16 shanks. As far as I can measure without a temperature controlled workshop and un-calibrated mics and Vernier callipers (real Vernier, not digital) they are parallel and consistently Ø15.98. However I may just have been lucky and some out there may be a bit more variable.

Martin C

Thread: Confused about lathe.
05/12/2018 14:50:26

Ian, an earlier post says he's in lumpy Lincolnshire so probably the wolds but there are also hilly bits like the Lincoln Edge and around Grantham.

Martin

Thread: Are Stevenson's ER Blocks Useful
04/12/2018 18:33:26

Andy, if you want something that goes beyond the square and hex blocks consider the Stevenson's 5C indexing head with ER32 adaptor and nut as sold by Ketan.

Martin C

Thread: Unusual Tool
02/12/2018 14:33:31

Button remover.

Martin C

Thread: Cost effective way of measuring 90degrees very accurately on Milling machine
02/12/2018 14:29:47

That's a small machine with a heavy head. The weight of the head will cause the column to bend by a different amount when the head is high compared to when it is low. Is this going to cause a headache when trying for accuracy? My solution for working with a round column machine will solve the problem for this machine, use a 16mm parallel shank ER collet holder in a 16mm R8 collet. You can slide it down for short tools and either use it all the way up for longer tools or take it out and use R8 collets alone. No head raising or lowering required.

Martin C

Thread: Turning Welded steel
01/12/2018 15:11:51

Scaffold poles are usually galvanised. I hope you didn't breath the fumes. I also do not know what effect the zinc will have on the weld filler metal.

Martin C

Thread: Cost effective way of measuring 90degrees very accurately on Milling machine
01/12/2018 15:04:54

The problem if you square up the column is that you may introduce an error in spindle movements. How do you know the machining for the column and the machining for the spindle are perfectly parallel to each other?

Martin C

Thread: Chester Super Lux - Motor Failure
25/11/2018 13:12:41

As Neil says don't get a 250V capacitor. Mains voltage of 230V rms has a peak voltage of 325V. Unless you know for certain that the 250V is an rms value you run the risk of rapid failure again.

Martin C

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