Member postings for Robin

I have the ML10. The biggest problem I find is cutting cast iron, the dust gets trapped between the bed and the saddle. I have all sorts of squeegees fitted trying to keep it out, but eventually it needs tearing apart, washing out with paraffin, particularly in all it's important little places, then reassembling with a quality lube. You can't wash it out without removing the saddle, how I have tried

I buy Myford slideway oil off ebay,

ISA VG 68 (FEBRIS K68)

Mobil Vactra No. 2 - 1 Litre

Whatever that lot means

A Raspberry Pi has a password? How unfriendly can you get? I thought they were supposed to lead people in to programming not stymie and frustrate them at every turn. Have you tried "password" because that is the only logical response to such a stupid idea.

Let me try that again, I'm going to do this...

*Link*

I have to Add Posting before I know if it's worked

Edit: I think that works, but when I hover over your Links I see the destination in a pop up box, not so with mine.

Edited By Robin on 18/02/2018 14:14:21

Today I am looking at the possibility of a small die casting machine

Here's a Wikipedia page Link​ with a drawing of a cold mould

The cavity is on the ejector side which looks totally wrong from a plastic perspective.

Does zinc not shrink as it cools? Very poetic today, cold mould, zinc shrink...

I am misunderstanding something?

That Link looks totally bogus https://en.wikipedia.org/wiki/Die_casting

Aha! So the picture of planet Earth rising over the Lunar horizon is for posting Links

Here's a thought, microswitches may have great hysteresis but they also bounce

Here's a nice one, £1.50 from RS, will a link to the RS data sheet work?

https://docs-emea.rs-online.com/webdocs/0d1b/0900766b80d1bd95.pdf

The Schmitt trigger gives it a natural hysteresis. It would need some way to keep a steady current through the LED which is why a separate Voltage regulator would be extra nice.

2um hysteresis is slightly OTT, it could ring like a bell, which is why you want that Schmitt trigger.

For accuracy it's very own Voltage regulator would be a good idea and a dust/light proof housing.

This seems a bit like more money than sense, not that I can't see the attraction, but wouldn't it be much more cost effective to get a Schmitt trigger photo interrupter and make your own switch?

I have a Roland, wax chopping, desk top mill that I have been hacking. It has microswitches for the limit switches and a dinky co-ordinate display on the Z head.

I have a home command to bounce it off the limit switches and set X, Y and Z. Repeated homing starts off okay for the first few times then it starts to creep.

I expected a bit of plus minus but not a creep. Seriously weird but never more than one click difference from one home to the next on a 5um step.

I bought 3 Omron precision switches from that auction site. I beat the poor chap down on the price because I was the only interested party. They do North, South, East and West with 1 um repeatability. I realised that what I actually needed was up down so I had to add an extra lever. Then I realised I would have to remake the entire mill controller and it has all sat on the shelf ever since

j

Is HMG's crackdown on acid throwing hooligans going to make it difficult to get sulphuric acid in sufficient quantity for that anodising tank?

I am really worried about posting on these things because there is a huge risk of teaching Granny how to suck eggs and getting accused of all sorts of Smart Alecry. I've only been on here a few months and I didn't read the whole site, but In for a penny in for a pound, here we go...

I would guess machine and tool shank bending. We all know the difficulty in machining off that last thou. You advance .001" and make the cut, no difference. You repeat, nothing and then blammo, .004" undersize.

The tool puts up resistance to the cut, it would rather rub and bend everything than make the cut. Only when it can no longer resist the cutting pressure does it make the cut and then it takes everything available.

There has to be enough pressure to get your cutting edge under the surface. I have a notion that enough cutting teeth means one is always engaged and hold the tool against that surface when the next one arrives.

A scalloped surface may be indicative of a tool that is oscillating between rubbing and cutting. Everything bends while it builds up the cutting pressure and then blammo. To counter an oscillation you change feeds and speeds hoping to find a natural damping. You reduce overhangs wherever possible. You cut down hill to try and minimise the overshoot. If this were a production environment you might even consider unequal helix tooling.

Talking of carbide inserts, I was turning some ball screws down to fit pulleys and bearings and stuff. They seemed to have a hard case, possibly work hardened after a tough thread rolling.

The insert invariably broke and then cut. The shattered tip worked better than the original sharpness.

Made me wonder if I knew what I was doing. Life is mostly surprises for me, I muddle through somehow

Interesting question. Of course the normal HSS tool tip sinks lower and lower with every sharpening until you have to grind it all the way back and start over. The tangential must have similar problems should you deviate from it's set shape.

When rummaging through the box of stubs and nubs looking for a volunteer to become that new tooth form you can often avoid a lot of grinding by simply turning it sideways on or upside down.

The tangential is probably much the same, but it is damaging my brain trying to visualise it

Posted by Tim Stevens on 09/02/2018 12:37:36:

I recently saw a parting off tool like that and thought what a good idea, but then I wondered how it would stand up to a hammering from anything out of round. Didn't know it was tangential. I actually made one about 10 years ago to get a set pointy angle from a normal Eclipse HSS blank. Never finished that machine, but if you gathered together all the machines I haven't finished you would understand my workshop

Appreciate the explanation

Robin

What is tangential HSS? Am I missing out on something good? Twelve percent of users, who expressed a preference, said their machine centres preferred it. Is this the new, must have accessory for 2018 or am I, as usual, the last one to know?

1 slg is the mass that accelerates at 1 ft/s/s when acted on by a force of 1 lbf.

But we should use the Poundal.

1 pdl being the force that accelerates a mass of 1 lb at 1 ft/s/s.

To complete the set, 1 lbf accelerates a mass of 1 lb at 1G.

My problem is that the slug has lbf in it's definition so it should be measured at Greenwich to be truly Imperial.

But if the lb is defined against the standard kg maybe you measure it at Paris.

Instead it is usually defined at the Equator which is neither here nor there.

My brain hurts.

Posted by norman royds 2 on 04/02/2018 16:16:58:

One a penny two a penny

This is not decimalisation, this is BOGOF

Don't get it. To steady an inside skim I would expect some kind of 3 point jobbie. Maybe I have had another TIA, my brain has become unreliable

I thought CE marking electrical goods was to say it didn't interfere with the telly. If you made an electric drill which obviously would interfere the boss had to sign a piece of paper to say it wouldn't.

Then TV's went digital and it all became irrelevant.

I was looking to pay thousands to have a computer card tested. The bod looking to relieve me of the money told me that i had to supply the computer to test it in. I said, "You're testing the computer aren't you". He did not disagree so I labelled the product as only suitable for use in the closed magnetic environment of a computer case, headed it, The Electromagnetic Compatability Regulations 1992 - (S.I. 1992/2372) and my customer became a happy bunny again.

The one I really hate is the RoHS lead free solder nonsense. Trying to solder with practically pure tin is very hit and miss. Nuff said.