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Member postings for JasonB

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

Thread: Part built Allchin 1.5 inch
22/08/2019 10:58:46

This should make it clearer for cold setting.

dsc03739.jpg

Once in steam as the boiler expands the cylinder will move away from the crankshaft so everything moves to the left but the piston does not so the 45thou gap will increase and the 80thou gap will decrease and hopefully end up equal.

22/08/2019 10:46:58

Derek, I'm just going to alter what I posted, got the cover without a spigot the wrong way round.

Thread: screw cutting on a chester db10 lathe
22/08/2019 10:44:17

If you can confirm which model you have and whether it is imperial or metric that will make it easier to help, ideally post a photo of the manual page or chart on the machine cover.

Once you know what the diagram is showing it is quite simple, must be as I seem to manage OK with my similar machine.

J

Posting photos

Thread: Further Adventures with the Sieg KX3 & KX1
22/08/2019 10:32:15

Ron, the work is set to stick up vertically on a rotary table and then a boring head with a tool suitable for cutting external diameters is positioned above and set to the flank radius of the cam. The work is then moved sideways and as series of plunge cuts are taken which form one flank.

imag1507.jpg

You then turn the rotary table a degree or two and make another plunge cut and keep on doing this which slowly forms the base radius.

imag1508.jpg

You carry on until you are left with just the width of tip required

imag1509.jpg

Once the milling is complete the tip is rounded by filing and any slight facets blended away. As the cuts are a large arc you get less obvious facets than if holding the cam horizontally and cutting with the end of a milling cutter but they are still present.

imag1510.jpg

Thread: Part built Allchin 1.5 inch
22/08/2019 10:20:27

You should aim for an equal amount of clearance from the cylinder covers each end when in steam so a little less at the back (chimney end) when setting it cold.

Drawings show cylinder 2.094" long less front cover spigot 0.062 gives 2.031" clear cylinder length

Piston 0.406" long + stroke 1.500" = 1.906"

2.031 - 1.906 = 0.125" divided by 2 gives 0.062" or 1/16" clear from covers at each end.

Therefor when hot piston should be 1/8" in from the chimney end and in 1/16" in from crankshaft end. Doing it cold I would say something like 0.107"  (45 + 62) from chimney end and 0.080" from crankshaft end

 

 

Edited By JasonB on 22/08/2019 10:53:08

Thread: Hex Silver Steel/Tool Steel ??
22/08/2019 09:27:46

Thank's Andrew, I will go and correct it. embarrassed

Just as well I did not use the American term of prick punch when I suggested also making a dot punch

22/08/2019 07:11:03
Posted by Christopher judd on 21/08/2019 16:44:06:

Hi Jason, I already changed my mind from using mild steel. Now going the 6mm silver steel route for entire thing. Like your idea. But questions in relation to your method.

1. Why use silver steel for end piece would o1 be as hard when hardened? Can't see reason for silver steel other than needs to fit exactly into drilled hole.

If You look back at the replies to your questions you will see one from Andrew "Silver steel and gauge plate are sold in the UK as such and are roughly equivalent to W1 and O1" It is basically the same thing, if you did not read American books you would not be talking using common American terms. Nothing to do with fit as I would not have said a drilled hole if things needed to be exact.

My suggesting allows you to still use readily available hex stock but have a point that can be hardened

2. Would loctite hold as it will be subjected to shock? Any recommendation as to which loctite??

Provided the end of the "point" was up against the end of the hole there would be no problem, on clock work you will only be needing a light tap not a whack with a lump hammer. I tend to use Loctite 648 for most things but 638 would be more than adequate.

Just got new (used for £15) book Table Top Machining by Joe Martin at face value really good.

Regards

Chris

 

Edited By JasonB on 22/08/2019 07:11:59

Edited By JasonB on 22/08/2019 09:28:14

Thread: Further Adventures with the Sieg KX3 & KX1
21/08/2019 16:11:37

While others prefer to discuss the shape of their heads I found a bit of time to run the CAM for some cams. In the past I would either have used CamCalc with multiple offsets of the mill at angular increments around the cam or used the inside out boring head method particularly on cams like this with a flank radius. Both of which take a while to setup and in the CamCalc case a long while to cut.

This time with 0.4mm deep x 5.5mm high roughing passes and a slightly slower fed 0.2mm DOC finish pass on the silver steel the cam was done in 2.30mins with no need to do any blending with files after. I can't see me wanting to go back the the old ways of doing things.

 

 

Edited By JasonB on 21/08/2019 16:42:17

Thread: Torx head variant or faulty batch?
21/08/2019 16:05:32
Posted by Barrie Lever on 21/08/2019 15:24:26:
Posted by Neil Wyatt on 21/08/2019 14:23:14:. Each province of China has a legally enforced minimum wage

Neil

(there is no Chinese National min wage as you mentioned)

Think you need to read it again Barrie, Neil did not mention a National minimum.

Can we now keep the talk to the subject of Torx

As someone who can often get through a 1000 screws in a week it is quite usual to have the odd duff one or two with either poor heads or plain shanks without the screw part being formed Seem to remember the same thing with old Nettlefold screws as now with screws that I don't know where they are made. I Just bin the duds and get on with it.

21/08/2019 15:23:34
Posted by Clive Hartland on 21/08/2019 15:18:57:

My answer was to put a screwdriver against and wipe it out.

That's not the model engineers way of doing things Clive, you know you should have spent the next three years contemplating making an EDM machine to modify your existing toolssmile p

Edited By JasonB on 21/08/2019 15:24:07

Thread: Hex Silver Steel/Tool Steel ??
21/08/2019 15:07:18

Another option as you are only going to be doing light punching would be to get some easily available 6mm or 1/4" hex mild steel and drill say a 4mm hole 25mm into the end and Loctite in some 4mm silver steel that has previously been turned to a point, hardened and tempered.

While you are at it make a matching dot punch which is used first to accurately place a small indent that can be pulled over to correct any drift before enlarging the mark with a centre punch.

This would still give you the practice with harder material, The hardening & tempering process as well as drilling holes. You would also have a usable tool at the end rather than a mild steel one that is no good to anyone.

punch.jpg

Edited By JasonB on 21/08/2019 15:09:00

Edited By JasonB on 21/08/2019 15:21:07

Thread: Home Workshop Site
21/08/2019 12:15:52

With a few e-mails between Ketan, myself and David Corner who is able to place adds without having to get them approved we have now got a notice up on the site

Thread: Call for Classified Ads for MEW 285
21/08/2019 11:57:17

~ = Approximate

Thread: Water pump dimensions
21/08/2019 08:55:46

This video shows the pump quite well, about half way through you can see that the ram lifts a little more than it's diameter so 1/2" stroke.

20/08/2019 20:50:34

You only need to look at photos of other engines to see what the offset is, look at teh gear behind the eccentric, no way is it offset by 1/2"

20/08/2019 20:40:48

Yes Jeff, altered it now

20/08/2019 20:26:42

Drawing says ream 3/8" and shows ram as 3/8".

1" stroke does sound too much for that engine, he did use 1" stroke for the larger horizontal pump but 1/2" stroke eg 1/4" offset is more likely. By comparrison my 2" Fowler is 3/8" bore x 3/8" stroke.

Edited By JasonB on 20/08/2019 20:41:07

Thread: Profiling tools
20/08/2019 07:51:44

Does say "box of 5" and around £4 a go would be right for reasonable quality. You could also try APT who will sell you a box with just two inserts of a slightly better quality.

Can't say that I use my one of these cutters very much but do use grooving & profiling type with the 2mm dia end more.

20/08/2019 07:06:07

A lot will also depend on material both type and diameter. Brass cuts easily but if too slender the cutting tool will deflect it and more chance of chatter. Stick out can also be an issue when clearance for the ball turner means the work is a long way out of the chuck.

Your 75mm figure would be if the whole insert were touching, at the most only half will be in contact so 37.5mm and even then as you get further around the tool the depth of cut lessens to nothing.

This form tool probably had a contact length of 30mm on my 280, stock is 16mm square

Biggest issue using a round insert as shown in teh video is the large fillet you are left with where the ball joins the stock which becomes proportionally greater as ball diameter decreases and the wide cutting action of the "blunt" round tip will put more load on the work needing a larger dia contact with the parent stock, an RCGT rather than a RCMT would help a bit as the edge is sharper as would going down to a 5mm dia insert to reduce fillet dia and contact length.

 

Edited By JasonB on 20/08/2019 07:26:24

Thread: Classifieds
20/08/2019 06:51:22

You do not need to post any more to place adverts.

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