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Member postings for Glyn Davies

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

Thread: Setting lathe top slide angle accurately.
25/12/2018 11:37:43

If I need to set the top slide to match an existing taper, such as a Morse taper, I hold some silver steel bar in the chuck and use a DTI to check that the top slide is set to zero by running it along the silver steel. I then slacken the nut clamping the Dickson tool post body to the top slide and bring the plain face of the body into contact with the silver steel. Then lock the tool post. I next fit the taper I’m trying to match into the chuck, release the top slide lock screws and bring the plain face of the tool post into contact with the taper. Then lock the top slide and turn my taper.

Thread: Cheap 3D printers
08/11/2018 19:40:42

Thanks for the replies - time to dip a toe I think!

08/11/2018 13:03:48

Hi Sorry if this is a question I could answer with a quick search, but - I just had a look on Amazon for 3D printers and couldn't believe how cheap they are, Some less than £200.

My question - if I buy a printer with a heated base plate, can I create prints in ABS or PLA from CAD models that I export as STL files? Is it really that cheap and simple? Will the printer come with software to slice the STL file and then print it?

Thanks

Thread: Small Carronade model - 68 pdr.
15/09/2018 13:18:50

As regards bluing the metal - I think you'll find that the sodium nitrate is now classed as an explosive precursor so that, for our safety, the freedom we once had to buy it has been removed.

An option is to rust blue it. You can still buy ammonium chloride (sal ammoniac) on ebay and if you dissolve 2 grammes into 100 grammes of water, you have an effective rust bluing solution. I'd try on scrap steel first and see if you like the result. Method is to swab the solution sparingly onto the degreased steel and leave supported above a dish of water for a couple of hours until a light grey/brown rust forms on the surface. Then immerse the item in boiling water for a few minutes, let it cool and rub off the loose fine rust with 0000 wire wool. Repeat the swabbing, rusting, boiling and wire wooling five or six times until the metal looks a sort of grey colour after the final wire wooling. The last step is to rub in some linseed oil, which will give some corrosion protection and turn the colour from grey to blue/black.

You can actually use sodium chloride at a pinch(!) in place of ammonium chloride but the process might take longer to get to a good blue.

Thread: Painting anodised aluminium
05/09/2018 08:58:42

I thought the last step in anodising after the oxide surface had absorbed the dye was to seal it by boiling in straight water. Anodising is easily removed by immersing in caustic soda solution for only a few seconds. You can tell if the anodising is gone (apart from the colour disappearing) by touching the surface with an ohm meter. The anodised surface will be non conducting, if you have conductivity, the anodising is gone.

I don't see why anodising would prevent paint adhering though.

Thread: Peace Flame
13/08/2018 16:46:00

img_2693.jpg

 

Thanks for the replies. Following Jason's suggestion, I took the burner off a butane stove and lit the jet. The control knob is just what I want. But how to get it apart to see how it works without wrecking my stove?

I assume the valve is seeing the full vapour pressure of the butane (about 30 psi or 2000mb).

 

Edited By Glyn Davies on 13/08/2018 16:55:05

13/08/2018 15:31:03

Hi

I could do with some design help, please.

I'm tasked with producing a propane fired peace flame for the village. The enclosure will hold two 3.9kg propane tanks with an automatic changeover valve that switches to a full cylinder when the first is empty. The valve incorporates a 37mb regulator. We have been given a ruby pilot jet from a portable gas heater.

When fed from the 37mb regulator, the flame from the pilot is too large and will consume too much gas. So I produced a manifold with a tapered screw to throttle the gas flow and reduce the flame. Here's the drawing of the manifold:

2.jpg

The problem is that the adjuster has to be screwed in tight to get the flame down to what it needs to be. I was disappointed that screwing the screw in tight does not completely shut off the gas flow and it is very sensitive. Screwed fully in, here's the flame produced:

img_0041.jpg

The flame size is about right but I want a finer adjustment. Can anyone suggest a better design for the throttle that will completely shut off the gas and allow fine adjustment at the very low pressures and flows pertaining?

Thanks!

Thread: Zeus book download
28/07/2018 17:59:37

Thanks Bob - what a gem that Presto book is!

28/07/2018 13:09:06

Thanks Vic!

28/07/2018 11:31:12

Thanks for the replies. I've been given the job of designing and making a burner manifold for an eternal peace flame for the village. I'm trying to figure it all out in CAD and it has numerous metric and UNF screw threads and it would have been nice to have the screw thread data that's in the Zeus book on my PC.

Gosh - I have two Zeus books in the workshop - a 1980 one that I use all the time and a 1995 one that I bought as a spare. I've just bought the 1995 one in and see that the table of BA thread data has been replaced by a metric fine one. What's the world coming to?

28/07/2018 08:51:59

Hi

Does anyone know if the Zeus data booklet is available as pdf download. A google search takes me to sites that ask me to create an account before I do anything and ebay just lists the booklet itself. I'd happily pay the price of the booklet for the pdf file.

Thread: Myford Super 7 Clutch
26/07/2018 19:10:33

Hi

The clutch on my S7 started slipping under heavy load (maybe it was a mistake to oil it to stop it squeaking) so I decided to dismantle it and clean it.

I decided that making a simple compressor wouldn’t be too hard, so I set to with some 4mmx30mm hot rolled bar, 6mm screwed rod with four M6 nuts and an M8x60 bolt from B&Q.

I cut two pieces of bar 56mm long, bored a 7/8” hole in the centre of one and drilled and tapped two M6 holes on 41mm centres. The second piece had an M8 hole in the centre and two 6mm clearance holes on 41mm centres. I then cut two pieces of M6 screwed rod 180mm long. Using my mandrel handle, I centre drilled the end of the M8 bolt in the lathe.

Here are two pics of the compressor:

img_2671.jpg

img_2684.jpg

To use it, I split the compressor and slid the bar with the 7/8” hole past the circlip groove in the countershaft spindle, fitted the circlip and then assembled the compressor. I then screwed the M8 bolt until it contacted the ball bearing and used a screw driver to unscrew the push rod off the driver plate.

Here are some pics of the pushrod and spring.

img_2668.jpg

img_2670.jpg

I hope this is of some help to others contemplating dismantling the Super 7 clutch.

Edited By Otley on 26/07/2018 19:23:08

Edited By Otley on 26/07/2018 19:32:39

Thread: A beginners' guide to aluminium anodising?
19/07/2018 09:42:07

I have tried this, using this article as a guide: **LINK** and got good results, with or without the dye.

I bought the black dye as crystals from ebay, a Chinese constant current power supply, also from ebay, used roofing lead as the cathode and aluminium MIG welding wire to hold the components being anodised. I modelled the components in CAD to calculate the surface area and hence the required anodising current.

One thing that surprised me was how effective the anodised layer is at not conducting electricity - touching the surface with the ohm meter probes shows infinite resistance. But dunk the item in caustic soda for a few seconds and the anodising is gone and conductivity returns.

Apart from all the stuff you need to do it (tank, power supply, battery acid, dye, lead cathodes, work holders etc) what I found a faff was the time required for each stage - anodising, dying, sealing. That's about three hours to do one small component. I'd consider making the part out of black Delrin if you can and save all the trouble.

Thread: Myford Super 7 binding spindle
11/07/2018 09:20:03

As an additional precaution, I firstly slacken the bull wheel grub screw, then adjust the spindle bearings and then tighten the bull wheel screw to give the correct drive pulley end float.

Thread: Cannot reply to enquiry
10/06/2018 08:09:46

Thanks Jason!

10/06/2018 07:43:48

Thanks Jason. Could you delete my advert (Myford lathe and accessories) and I'll relist it with a phone contact number and a request that emailers include their email address?

10/06/2018 03:14:31

Hi

I have placed a classified ad and someone has emailed me with an enquiry. I tried to email a reply to the enquiry but my email was rejected. I got the following error message: Your message couldn't be delivered to alerts@model-engineer.co.uk because the remote server is misconfigured. See the technical details below for more information.

How do I reply to classified ad enquiries?

Thanks

Thread: Motor wiring
05/06/2018 20:24:48

Just had another look at your pic - it looks as though R and P are the centrifugal switching connections - there should be zero ohms across them. It also looks as if blue and yellow are the ends of the start winding and red and black the run winding. Confirm with an ohm meter. If so, you should connect the red/green cap wire to R, the red wire to U1, and the black to U2. You then need to connect the live run supply to U1 and the neutral run supply to U2. The live start supply goes to P and the neutral start supply to the yellow wire. Hopefully one of the screw studs is not connected to anything in the motor and can be used to connect these two.

If you don't have a reversing switch, bridge U2 and P and connect the yellow wire to U1. Then connect the live from your switch to U1 and the neutral to U2.

If you follow these instructions, stand well back when switching on.

?

?

Edited By Otley on 05/06/2018 20:28:25

Edited By Otley on 05/06/2018 20:52:55

05/06/2018 19:53:29

I was faced with a similar problem when trying to wire an imported motor to a Dewhurst reversing switch. I hadn't appreciated that both sides of the start winding centrifugal switch are connected to terminals in the connector box. In my confusion, I managed to wire the incoming live and neutral across the switch. Not a good idea.

The basics are that a capacitor start motor has a run winding that has a resistance of 3 ohms or so and needs a live and neutral across it. The start winding also needs a live and neutral across it but has a slightly higher resistance and has a capacitor and a centrifugal switch in series with it. Swapping the live and neutral across the start winding reverses the motor direction of rotation. In my case, one of the loose wires was one end of the start winding and the other was a short wire from the output side of the centrifugal switch. I therefore needed to make two soldered and heat shrink sleeved connections - wire from switch to capacitor and capacitor to start winding. The two pairs of lives and neutrals could then be attached to four of the terminal posts.

If you see what I mean...

In your case, it looks as though the run winding is connected to U1 and U2, but why you have three loose wires as well as the cap wires is a puzzle and you might need a ohm meter to figure what's what.

Thread: Automotive Products, Leamington
06/03/2018 13:40:24

I haven't used it because I just have too many vices...

p1000616.jpg

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