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Member postings for John Stevenson

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

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Thread: MEW 162 - Phoenix Battery Drills
22/03/2010 13:16:16
What about publishing articles in the magazine that have an element of risk attached  by using white text on white paper ?
  
That should please all the flat earth society.
 
.John S.

Edited By John Stevenson on 22/03/2010 13:17:15

Edited By David Clark 1 on 23/03/2010 12:06:31

Thread: Thread dial indicator
22/03/2010 13:05:59
Usual build up is 4 times the thread pitch for the gear so for an 8 tpi screw you need a 32 tooth gear.
Looking at the lathe in question this looks about correct
 
Bad news is that to mate with a 8 tpi screw you need a gear that is measured as Circular pitch, CP, as opposed to a normal gear of Diametrical Pitch DP
Also this gear has to be helical to follow the helix path of the screw.
 
So you are looking for a helical gear of 0.125 CP or  25.13 DP
 
Good news is because this is only driving a dial you can ignore all this and fit a normal gear of 24 DP and it will follow good enough for your application.
 
John S.
Thread: 3D in MEW
21/03/2010 21:56:50
Posted by David Clark 1 on 21/03/2010 21:50:17:

The easiest way to see 3D is to stare slightly cross eyed into a shopping trolley at your local supermarket.
If you do get the 3D effect it is really good.
regards David
 
 I always though that was a feature of the wheels being out of track.
 
You learn something every day.
 
John S.
Thread: Chuck
21/03/2010 17:45:12
I think that's one of Harold Halls home made items, can't recall seeing a tee slot faceplate for a Myford from any of the usual villains, sorry sellers.
 
John S
Thread: Cad for complete beginners (CAD for idiots)
21/03/2010 12:43:13
Missed a load Ian, the list is too long.
 
Never tried Double Cad, never managed to get past the download window.
I personally don't like Turbocad, it's too clunky having to fill dialogue boxes out for everything and jumping thru hoops for simple jobs.
 
I do agree though that unless you need a specific feature or you are doing it professionally then there is no need to pay for a program.
 
John S.
21/03/2010 10:28:15
If you are conversant with Autocad there are some programs that are free and based on that.
 
Alleycad is close,
 
http://www.allycad.com/freeware.asp
 
the freeware copy will only open and work on drawings up to 300K, after that you pay  for features but the paid for versions are either encrypted or dongled.


A9CAD is another close copy,
 
http://www.a9tech.com/
 
Freeware, no limitations,
 
Progecad has a verion called Smart that is so close to Autocad it's hard to see which program you are using.
 
http://www.progesoft.com/en/smart-2009
 
No limitations and they have their own user forum.
 
 
Cad is like religion, one copy will not suit everyone. It's no good taking someone's recommendation that theirs is the best program. You can see this in the replies above where many different programs have been touted.
 
CAD is a learning curve, how steep depends on the user but the first part is to download at least 4 or 5 demo's and spend at least a full night with each to see how the way it draws suits you .
 
If you are not prepared to put this level of work into finding one you will never get the best out of a program. It sound s a lot of work but once you are proficient with a program it pays back in spades as regards accuracy and production.
 
John S.
20/03/2010 18:32:12
One thing to watch if you choose a 3D program, as Peter has said some are Modelling programs often related to generating games and art type figures.
 
Some of these cannot generate 2D drawings from the 3D information and it would be a shame to spend ages learning a program only to find that all you have are pretty pictures and no way of getting a workshop drawing out of it.
Thread: Tony Jefree`s CNC conversion of the Myford ML7 Lathe (MEW May 2008)
20/03/2010 16:49:58
The ML7 can be modified by just modifying the bracket, the rest isn't touched and this is to fit one ball race and two needle roller thrusts.
 
The same applies to the Super 7.
 
The S7 PF is a different animal as it has a larger bearing diameter that cannot be reduced because the bearing diameter is 9/16" and the screw is 1/2"
Also there is a cross drill hole to take a pin that knocks the power feed out if left unattended, boring into this will weaken the pin.
 
 In this case only the needle thrusts are fitted to get zero backlash but it means the bracket, screw and dial have to be machined.
 
Because it's a "Myford" many of the flat earth society, sorry purists, will not do this because it's not British Standard Myford.
 
You make your own choice.
 
John S.
20/03/2010 09:04:51
David,
I'll get on to them this weekend and keep in touch.
 
John S.
20/03/2010 08:37:42
There are actually three different cross slide arrangements for the Myford.
The ML7 which has a 3/8" bearing diameter.
The Super 7 which has a 1/2" bearing diameter.
And the Super 7 with power cross feed which has a 9/16" diameter.
 
I have done conversions for all 3, well 2 actually as the ML7 was already done and this is being written up for MEW and Ketan at ARC is making the kits up.
 
John S.
Thread: Gear milling
05/03/2010 12:29:43
Both sets of tables are correct if used in their entirety and not mixed up.
Where the differences are concerned is where the infeed position is calculated from.
 
In Ivan's book   [ brilliant book BTW a must read if you are into gear cutting ]   he calculates the infeed by touching the outer edge of the button on the blank, moving over to centralise then infeeds the distance in the table.
 
In the web article which was taken from calculations done by Grant in 18 ought plonk, the infeed is taken from a point where both buttons radially touch a blank of known width, [ W ], and then infeeds from this point.
 
It's not easy to spot the differences between the two methods and this causes the tables to be different.
However if you drawn these out in CAD and overlay them, the differences are minute  and both follow very closely a precise CAD drawn involute.
 
John S.
 

Edited By John Stevenson on 05/03/2010 12:30:35

Thread: Has anyone any experience of HQSS tools – notably taps and dies?
22/02/2010 00:57:48
If you do a search on HQSS only this company refer to it.
 
I could find no reference to it anywhere else which make me very suspicious that a small import company has access to something that none of the high end companies has or needs to invent.
 
John S.
Thread: How to prepare Hot Rolled Steel for marking/machining
18/02/2010 22:21:21
You want some stuff called Phosphoric Acid, it's sold at B&Q as brick and cement cleaner, look at the labels and try to get one that 90or 95% acid.
 
Plastic tub, mix it 3 or 4 :1 with water and put the steel in overnight and the scale flakes off.
 
It's not a nasty acid, best to wear rubber gloves but it doesn't sting or burn, when used up it can go down the drain or wash the slabs with it.
 
Unlike some of the other acids it doesn't make nasty fumes, I have a tub on the floor next to a big dividing head and it been there for 2 months now and no rust or anything.
I descale about 100 disks per month using this method, they come out with a grey sheradised finish and if you lightly oil it that's all that needed.
 
I dropped a scrap tap I found in the base of a lathe, been there 40 odd years, all rusted up and grungy, Stuck it in overnight just to see and it came out next day grey all over and like new, it even felt sharp !!
 
John S.
Thread: Has anyone any experience of HQSS tools – notably taps and dies?
13/02/2010 20:30:47
I did the same search a while ago and wondered if it's that good why aren't other companies using it ?
 
Cross referencing prices I can buy branded from J&L cheaper, in some cases a lot cheaper.
 
John S.
Thread: Knurling
02/02/2010 21:52:22
Any idea why my picture has disappeared again ?
 
Been there all day now gone?
 
John S.
02/02/2010 09:42:21
I have proven that diameter isn't a factor.
I took a bar of steel and machined it into equal steps at random diameters, each diameter a few thou less than the previous one and ran a knurl along the whole length.
 
The whole length came out perfect regardless of diameter.
 
I do a lot of knurling that has to be accurate as regards no twist and even.
 

 
 
This is a 30mm steel bar knurled in one pass at 500 rpm and flood coolant.
 
John S.
Thread: Digital editions of Model Engineer and Model Engineers' Workshop.
31/01/2010 11:56:50
Same here with Issue 16, only gets to page 62.
 
John S.
Thread: bonded crankshaft
17/01/2010 13:54:46
.
 
He's perhaps deaf himself, or blind ?
 
.

Edited By John Stevenson on 17/01/2010 13:55:10

Thread: Signature Files
15/01/2010 09:26:13
If you are using Firefox look for an add on called WiseStamp.
It lets you select a few different signatures and insert them with a right click menu action, as below.
 
John Stevenson,
Nottingham,
UK.
Thread: Back plates for Harrison lathe
11/01/2010 22:53:44
Steve,
See advert #1832
 
http://www.homeworkshop.org.uk/

John S.
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