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Member postings for tractionengine42

Here is a list of all the postings tractionengine42 has made in our forums. Click on a thread name to jump to the thread.

Thread: Girder crown stays - are they overstressed?
19/12/2011 12:50:16
I have had some email correspondence with Paul regarding his original post, “Are my boiler stays over stressed”.

To answer his question I carried out an FEA (Finite element analysis) based on the drawings of the Durham traction engine boiler by John Haining. The results are shown below.

The materials are all copper except for the boiler firebox side stays which are specified as bronze.

The analysis confirms that, for the copper crown stays, the stresses at an operating pressure of 90 psi range between 6 and 24 N/mm2 well within the design limit of 26 N/mm2. (3770 psi). This stress is much lower than the 113 N/mm2 (16400 psi) which Paul calculated correctly for a simply supported beam.

The bronze stays have a maximum stress around 50 N/mm2, again well within the material yield strength.
 



This analysis verifies the original designer provided a very sound design which has been demonstrated by the many examples in steam for many years.
 
Nigel

Edited By tractionengine42 on 19/12/2011 12:52:30

Thread: Morse Taper Removal
17/12/2011 03:20:22
Here is a simple solution by a Sherline owner.
 
It's cnc machined but can easily be modified for other machines and convensional manufacture. Does require the spindle to have some extension available though so, in this respect, may not be a universal solution.
 
 
 
Nigel

Edited By tractionengine42 on 17/12/2011 03:21:26

Thread: Girder crown stays - are they overstressed?
09/12/2011 00:51:43
Paul, if it interests you I can look to do some fea analysis, I will need a copy of your boiler drg. or sketches etc.
 
FEA does have limitations and results have to be viewed with such limitations in mind. Allot depends opon the users knowlede of the application and skill in preparing the simulation however, it will give a clearer picture. The analysis will be linear, that is it assumes all strain is elastic no account being takes of re-distribution of stress in areas of high stress concentration etc. This can distort results a little.
 
All I am saying is, it's not the be all and end all but can improve understanding of the application, in that context it can help identitify how and where to make improvements.
 
If you want to take this further send me a PM.
 
Nigel
Thread: Copies of Old Model Engineer magazines on disk?
27/11/2011 02:09:38
Here is a previous post re. ME on CD.
 
 
Nigel
My link does not seem to work, here is the URL: http://www.model-engineer.co.uk/forums/postings.asp?th=33408

Edited By tractionengine42 on 27/11/2011 02:11:11

Thread: Vectric 2DCut and Mach3
19/11/2011 12:29:19
Hi ian
I use autodesk inventor for my work so I am able to use this for creating quite a few dxf and stl files for my cnc work. This software allows you to fit text to a curve.
 
If I can help you with a particular requirement send me a PM and I will see what I can do.
 
Nigel
Thread: what does this mean on a drawing
15/11/2011 15:41:11
Here is a useful tolerance chart
hole tolerance
Thread: Scriber
14/10/2011 18:01:31
I have been using a 0.1mm dia x 10 deg carbide engraving cutter, it has half it's dia ground away like a 'D' bit making the point 0.05mm. I have found it provides a good line for locating a center punch and hard wearing, thay are very cheap on ebay, just bought some 5 for 5 pound + 3 pound p&p. They are advertised as PCB engraving cutters
 
Just to clarify, I am not engraving the line, I am using the engraving cutter as a scriber, The cutter is 1/8" dia, I drilled the end of a 3/8" bar and loctited it in.
Nigel

Edited By tractionengine42 on 14/10/2011 18:06:20

Thread: Vectric 2DCut and Mach3
12/10/2011 15:29:53
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Ha Ha.
You did get me, for a moment I thought it was "back to the CNC" or should that be drawing board
 
 

Edited By tractionengine42 on 12/10/2011 15:35:26

Edited By tractionengine42 on 12/10/2011 15:36:45

12/10/2011 14:14:25
Result

1st Vectric 2DCut engrave
2nd Vectric 2DCut - pocket mill
Allchin Front Wheel Hub
Milling cutter 0.2mm x 20 deg engraving cutter, 8000 rpm, 200mm/min max.
23500 lines of code.
A liitle more conventional machine work to do then just need to infill with red enamel and polish
 
 
Nigel
 

Edited By tractionengine42 on 12/10/2011 14:19:17

Edited By tractionengine42 on 12/10/2011 14:26:21

10/10/2011 10:33:35
Hi
I don't usually look at a manual until I have broken something, so I thought this time I would get ahead of myself.
 
The mach 3 manual actually explains very well what John has advised and I can now begin to understand this absolute and incremental stuff.
 
This website seems very good if your just learning G-code, click on a g code and you can walk through a visual illustration of what the Gcode is doing. looks good to me anyway.
 
 
 
Nigel

Edited By tractionengine42 on 10/10/2011 10:44:03

09/10/2011 20:50:28
Hi John
Sorry to hear your frustration, it's such a waste of valuable time when these things happen.
 
You will have gathered I am very new to cnc but learning fast. Just this post has shown me allot by pointing me in the right direction.
 
My startup string only has G80 so I will add the others you mention. I checked the gcode on the programme and the codes you mention are at the beginning so I guess vectric is doing a good job there and all should be safe.
 
I am keeping my feed rates very low until I feel a bit more confident.
 
Cheers
Nigel
09/10/2011 19:35:39
Hi John
BTW, I also wish you had a pound for every time you have answerd my question, your worth every penny.
 
Thanks again
 
Nigel
09/10/2011 19:27:54
Hi john
Your second post must have arrived as I was making my reply.
 
Thanks for the additional info. Currently I am dedicated to metric so will have a look at what your saying.
 
I was thinking of having a metric and imperial configurtion and loading either via Mach3 loader. I assume that should work OK?
 
I was just wondering, the setting I have just changed from absolute to incrfemental, is there likely to be a circumstance where I would need to change it back?
 
 
Thanks again
Nigel
 
 
09/10/2011 19:18:58
Hi Guys
 
Jim, yes I saved under mach2/3 mm
 
John, I made the config changes you stated and it's now working perfect.
 
I obviously need to learn more about config options.
 
Thanks so much, I had not expected such a quick and easy solution, that's the power of forum's, superb community support.
 
Cheers
Nigel
 
 
 
 
 
 
09/10/2011 18:04:36

Here is a Preview from Vectric showing what the expected result should be.
 
Cheers.
 
Nigel
09/10/2011 17:46:28

Hi
I am just starting out on cnc and trying to use 2DCut to generate G code for Mach3.
I have tried several projects, some from dxf files and others drawn in 2Dcut but all with the same result.
 
All seems well in the 2DCut programme, the preview works OK. It saves the Gcode as a text file, when I load this into Mach3 there are masses of circular tool paths As can be seen in the above screen shot.. The actual tool paths wanted are in there (red lines) but obviously something is a miss.
 
Anyone using Vectric 2DCut and Mach3? Any ideas of what the problem is.
 
Incidentally I have used Meshcam to machine some test 3D shapes without any problem so I am sure this is to do with how 2DCut is processing the Gcode.
 
Any help appreciated.
 
By the way, I have tried to register with the Vectric Forum but it yells me my IP address is not permitted, hmm I have paid my money now.
 
Thanks
Nigel
 
PS. the profile I am trying to machine in this case is that of a Jaguar (cat). I will screen shot fron Vetric to my album to show the intended result.

Edited By tractionengine42 on 09/10/2011 17:50:05

Edited By tractionengine42 on 09/10/2011 17:50:43

Thread: Oil grooves in piston valves
16/09/2011 13:17:46
303 is the free cutting grade of st st, machines very easily compared to 316 and easily polishes to a mirror finish.
 
If you want to stay with the drawing dimensioins of 1/64 wide a 1/16 deep another method might be to mill them using a slitting saw in the mill. Put the part in a chuck on a rotary table, feed the slitting saw to cutting depth and slowly rotate the table.
 
Nigel

Edited By tractionengine42 on 16/09/2011 13:18:13

Thread: bearing material,
26/07/2011 09:39:27
Hi Charlie
 
I built the 10V many years ago.
 
I am sure the bearings are extruded brass but do not know what grade of brass.
 
Don't think you can purchase anywhere else, not that I have seen anyway.
 
Nigel
Thread: GETTING CNC WORKING
25/07/2011 16:03:42
Hi
 
Is your parallel port working in the correct mode? Do the drivers need EPP mode?

Here's my tale of woe:

I am having similar problems getting my computer to talk to my Gecko drivers correctly this last month.

Like you I am using XP, my drivers require my parallel port to be in EPP mode, if you have an on board parallel port it can usually be changed in the bios.

I do not have an on board port so I am using a PCI I/O card. Unfortunately for me, although the literature says it's EPP compatible when fitted it installs automatically in ECP mode and I can't find any way to change the config.

This seems to be why I can't get the system working, maybe you’re having similar problems for similar reasons.

Now I am trying to find a PCI parallel port I can set to EPP, hopefully one that uses a jumper setting so there is no option on installation.
 
I am not computer literate so I hope the above makes sense and maybe help you out.

The guys on Artsoft/Mach forun have been a great help.

Cheers

Nigel

Thread: Vertex Auto Tapping Head
19/06/2011 13:04:56
Thanks David
Someone is sure to put up a youtube video, so let me be the first this time. First time I have seen this operation/tool.
 
Richard, interesting tool. Good luck with it if you buy one.
 
Nigel
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