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Member postings for duncan webster

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

Thread: Type of builds on this site
05/12/2018 02:07:36

Why not write it up for ME or MEW. Then you get some dosh (a very poor hourly rate if my contributions are anything to go by), and possibly a wider audience

Thread: headstock oil
04/12/2018 13:18:17

Carl, the original query was about slideway oil which has 'tackiness' additives (see the link in peak4's post above). It is not simply mineral hydraulic oil. These additives are I think are gunging up my sightglass. I'm switching to 68 grade mineral hydraulic oil.

I would agree that buying 'special' oil for Myfords in little bottles is an expensive way of doing things.

Thread: Horn Antenna for Radio Astronomy
04/12/2018 11:50:54

To add a note of levity, if the OP makes second horn he could then make an acoustic radar set

see**LINK**

Thread: headstock oil
04/12/2018 10:56:48

Thanks chaps, after reading these comments I'm decided on the normal hydraulic oil. Thanks for the offer peak4, but I can get it from Caldo in St Helens, a lot closer but nothing like as pretty as Buxton

Duncan

03/12/2018 20:20:07

as I reported in a post elsewhere the sight glass on my headstock has an arrangement whereby a white screen is supported behind the glass to make it easier to read. This has now twice become bunged up with gunge making the sight glass look as tho there is oil when there might not have been. I only noticed when pouring more oil in didn't affect the level. The recommended oil (for everything, slides, headstock gearbox etc) is Esso Febis K68, which is primarily a slideway oil. They also state 'oil having anti-oxidation, anti-wear and anti-foaming properties and an approximate Kinematic viscosity of 68 centistokes at 100F'
Any lubrication experts know what they put in slideway oil to make it sticky? Could this be the cause of my gunge? I'm thinking of just buying Hyspin68 or similar hydraulic oil which seems to meet the verbal requirement.
**LINK**

It's a bit risky to continue with Febis, this is the second time this has happened
Lathe is myford 254

Thread: Learning CAD with Alibre Atom3D
03/12/2018 00:13:35

sorted, toggle sketches button turns the red lines off.

Then I closed down without saving. Not to worry, I've got the quarter sections so just mirror them again

Thread: Cost effective way of measuring 90degrees very accurately on Milling machine
02/12/2018 23:51:21

You can check the square by clamping it to the table along the x axis, running the dti up it using the Z, then reverse the square, run the dti up the same edge. If you get the same answer the square is OK if it is mirror image the square is wrong. With copious supplies of cold towels to wrap round your head you can allow for inaccuracy of the square. or easier put a bit of shim/tinfoil whatever under one end of the square when you clamp it down

Thread: Learning CAD with Alibre Atom3D
02/12/2018 23:31:39

nearly there, everything is constrained. I finished up modelling a 1/4 section then mirroring everything. Good job I'm not earning my living at it, still very slow.

Only issue now is getting rid of the red lines which are hovering.Wait for #2 son to visit again I think

Thanks again for your help

coupling rod.jpg

 

 

Edited By duncan webster on 02/12/2018 23:41:57

Thread: Motorcycle General Discussion
02/12/2018 19:13:49

So having found that it is out of true what do you do? Just hit it with a lead hammer, or do you scotch one side with a block to prevent it rotating?

This is probably becoming a lost art as Japanese bikes seem to last forever (I will now go and wash my mouth out)

Thread: Learning CAD with Alibre Atom3D
02/12/2018 18:52:00
Posted by David Jupp on 02/12/2018 17:36:46:

Duncan, having copied with base point and nominated the base point - use Paste Stamper, the base point that you nominated will follow the cursor and can be placed wherever you wish.

Thanks again, #2 son came round and gave me a teach in, if I can remember it I'll be a lot better. It would have been a lot easier not to know anything about 2D. He even managed to not lose his rag with his elderly parent being dim! Never mind I can still run rings round him on stress calcs.

02/12/2018 16:54:33

David, why not use inches? because I'm stupid! Much easier when I switched

Looks like I'm still thinking 2D, creating a round boss as one sketch, a rectangular lump as another then dimensioning the rectangle from the boss centre and symmetric about a vertical from the boss centre worked in about 10 minutes. I'd been hours trying to do it my 2D based way. Must try to think in terms of shapes rather than lines. Neil's way works as well, dropping a rectangle on top of a circle then trimming away the redundant lines

Just one more query for the time being, if I select a figure, (shift left click drag) then copy with base point and select the centre of the circle. Then paste, it puts a copy overlaid on the original just a bit offset to the NE. I would expect it to ask where to put it (no silly puns)

Thanks

sk4.jpg

Edited By duncan webster on 02/12/2018 16:56:32

02/12/2018 15:00:36

This is beginning to 'do my head in' as my youngest would say. I'm trying to model a coupling rod, so I draw the boss at one end, then a vertical line from the centre 1/2" long and a horizontal line 5/32" long. Then mirror the horizontal about the vertical, and using the constraints icon, lock these 3 lines. All very nice so far, everything in black and no error messages

sk1.jpg


If I then offset the vertical line either side I get 2 red lines,


sk2.jpg

but no matter what it won't let me lock them, I get an error message

a constraint cannot be applies as it results in an over-constrained or inconsistent sketch.

My simple mind thinks that if the first vertical line is constrained, then creating an offset to a dimension results in another constrained line, but apparently not
If I then trim the outer curve inside the red lines and the red lines back to the outer curve, the outer curve which was constrained becomes unconstrained, and it won't let me lock it, same error message. If I try to make it coaxial, it says the constraint already exists.
This continues if I just ignore it and offset the vertical line by half the rod length and then mirror the boss about this new line, all of the new boss is unconstrained, but won't let me constrain it. If I carry on it does produce a convincing model, but #2 son is full of warnings about lack of constraints. Not finished yet, got to do the fluting, but it would be nice to know I'm not going to have to start again
sk3.jpg


but there are 3 red lines left which I can't get rid of.

HELPPPPPP




































 

 

 

 

 

 

 










 

Edited By duncan webster on 02/12/2018 15:03:59

Edited By duncan webster on 02/12/2018 15:14:13

Thread: Cost effective way of measuring 90degrees very accurately on Milling machine
01/12/2018 21:20:09

taking Neil's cylinder square, if you move the Y axis ever so slightly back and to you will get the max even if te column is leaning front/back

Thread: What did you do Today 2018
01/12/2018 14:39:10

Today was time to top up the oil levels in the lathe. There was till a decent showing in the headstock, but might as well top it up. No matter how much oil I poured in the level didn't go up, so I drained it all out (not too easy on a Myford 254) and removed the sight glass. It has a clever design with a white screen held off the back by about 1mm so you can see it more easily. The little slots were full of gunge, so oil couldn't get in or out. Not too good. Cleaned up and refitted, if it happens again the white screen is going to have to go! This is something to watch out for if you have similar sight glass.

Thread: Machining cylinder castings from bar stock
01/12/2018 14:32:52

If you do you want to do it on a mandrel, I've had success by machining a close fitting mandrel, but not interference then having an o ring squeezed axially to grip. With my machining skills getting it to grip but not get stuck by traditional means is a non starter. If you adopt this approach, make it fit the larger bore first, unless you are confident of getting both bores exactly the same

img_3381 (small).jpg

mandrel (small).jpg

Thread: Boley & Leinen
30/11/2018 19:29:11

Bit of a mark up there I think see

**LINK**

Thread: Arduino DRO
29/11/2018 23:34:10

If P/R means slots then you are in with a chance as you would have 1600 edges. You can set the Arduino inputs (on 2 & 3) to be INPUT_PULLUP which adds a pullup resistor for you.

Thread: Tungsten Alloy
29/11/2018 23:18:20

Neil,

do you think I'm made of money? each one has a volume of 4804mm^3 which is 50 gms, £14, by the time I've allowed for machining that's going to be £20 each, £80 total. It's only 20% more dense than brass. You must have forgotten I'm from Yorkshire.

Comparing the Alibre model wit the real thing I realised that I had erred on the crankpins, so tonight's job was some precision application of the 2lb hammer to get the crankpins out and make some new ones from EN8. Good stuff this 3D modelling!

I ought to point out that the wheels are loctited to the axles, and the quartering is bang on, so I'm not inclined to take them off! Machining holes is possible I think using the horizontal spindle of the milling machine or even clamping them down on the lathe saddle, any profiling would be a lot more difficult.

 

 

 

Edited By duncan webster on 29/11/2018 23:26:24

Thread: Learning CAD with Alibre Atom3D
29/11/2018 19:56:49

Does the stricture on renaming apply also to moving files to a different directory?

Thread: Schmidt Couplings
29/11/2018 19:49:42

The LMS Turbomotive had one of these in the connection to the drive axle, very much bigger of course. I think GT3 gas turbine loco had likewise

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