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Member postings for blowlamp

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

Thread: lathe query
11/01/2012 09:44:50
No, it's nothing like half a degree and it's the cross slide, not the headstock that is inclined.
It's more like a thousand of an inch in four or 5 inches, but usually less in better lathes and is done for the reasons stated by Nigel B.
 
If the maker of the lathe could somehow achieve an exact 90 degree relationship between the bed and cross slide, then in time, some wear would result in uncertainty as to which way the lathe would now be facing-up i.e. convex or concave. So the maker just builds in a small safety margin to ensure it's always concave.
 
 
Martin.
 
Thread: Grinding on the side of the wheel
10/01/2012 22:28:41
Terry.
 
I'm not that experienced in their use, although I do have a couple of diamond wheels and they work well for finishing. They hold their shape well, but I still use a conventional stone for roughing out to form if much material needs removing.
 
I true them with a small diamond file, if and when necessary.
 
With regard to the dust. Don't forget that much of it will be composed of tiny HSS or carbide particles from the cutters themselves, so will be an abrasive in itself.
 
 
Martin.
 
 
10/01/2012 14:22:00
This issue has always puzzled me too.
 
My thought is that most common bench grinders that might be used in the home workshop would have plain wheels of around 13 to 20mm wide and so fairly robust.
 
I admit to having no knowledge about the manufacture or technology behind their construction, but I do wonder just how much pressure you'd have to apply in an axial direction to have one of these burst.
 
A saucer wheel looks much more flimsy to my eye and we are told is safe under similar circumstances of use - infact lots of cup type wheels appear to be weaker to me, in many more ways than plain wheels and yet these can officially be used on their side and periphery.
 
What you don't want is something being dragged in between the side of the wheel and its guard.
 
 
Martin.

Edited By blowlamp on 10/01/2012 14:23:16

Thread: Mill spindle trouble?
10/01/2012 10:49:46
Posted by NJH on 10/01/2012 10:22:49:
Hi John
 
You say:-
 
| "Indecently I don't know Hugh...."
 
 
But of a typo there I think - I hope you mean incidentally !!!
 
Regards
 
Norman
 
 
It's infectious too!
 
Only John knows what he really means
 
 
Martin.
 
Thread: Wheel Cuting thin tooth?
08/01/2012 10:16:44
 
The second wheel in your picture is duff at the 10:30 position.
 
The thing I notice in the third and last of your photographs is that the support arm of the indexing pin is anchored to the bench rather than the lathe.
 
If the lathe is able to move in relation to the bench - and hence the the arm - then a slight rotation of the headstock spindle will occur and give the error we are seeing.
 
Is the lathe firmly secured to the bench so that it can not creep across it?
 
 
 
Martin.
07/01/2012 09:24:58
Posted by Tel on 07/01/2012 05:34:06:
"Blank size won't cause this error; blank too small, all teeth slightly too thin and vice versa."

Ah, but what happens if the blank is the wrong size and the (correct) depth of cut is set on said incorrect blank? (I don't know, just posing the question).

Edited By Tel on 07/01/2012 05:35:10

Then all the teeth will be either too thick or too thin.
Think of a simple spoked wheel: at any given radius, all the spokes will measure the same distance apart provided, they are accurately indexed.
 
As long as things such as the part slipping whilst cutting aren't happening, or the original poster is using inaccurate equipment, then this appears to be a case of a cumulative error building up because of some kind of maths error by him.
 
If direct indexing is being used here and the fault shows every time, then the indexing plate must be faulty.
 
A good picture of the whole setup might help us here.
 
 
Martin.
Thread: Milling machine speed range
02/01/2012 13:06:53
Posted by MICHAEL WILLIAMS on 02/01/2012 11:51:09:
R J :
 
 
...If you want to use cutters 1/4 " and smaller including engraving cutters it is far easier to make a new small free running cutter head for the purpose and just fit it to a tool shank and drive from an auxilliary small motor via round belt . If you put part of the spindle and top bearing inside the tool shank the whole thing can be very short and rigid indeed . Even if your tool shank is too small to do this the set up is still much more rigid and short than the Stephens in line speed increaser and ten times easier to make .
 
MW

Edited By MICHAEL WILLIAMS on 02/01/2012 11:59:06

Agreed Michael. In fact just like the one I made and posted a link to a few messages back
 
Martin.
01/01/2012 17:10:04
I discussed the topic of high speed spindles on another forum last week and in particular of one I've designed and put together. So to avoid repeating what I've already said, here's a link http://www.cambam.co.uk/forum/index.php?topic=2207.0 I hope it's of some use.
 
 
Martin.
Thread: Warco WM-180 or MIni Lathe
30/12/2011 20:56:42
Now I know this is more than your stated budget, but if you can afford it, the Chester Comet VS lathe could well be worth considering because of its extra capacity and features. It's on offer at the moment too.
 
 
 
Martin.
Thread: iPad in the workshop, something to bear in mind!
28/12/2011 16:13:31
Greetings Terry.
 
I bought a Windows 7 Family Pack for three computers when it was first released and I'm fairly sure that it was less than the £70 per system that I first mentioned. The pack contains two discs with 32 or 64 bit operating system on each, so I can reinstall if I need to (I haven't thus far).
 
My understanding of Apple computers and viruses is that they aren't immune from attack, they just aren't targetted in the way as PC's are. A bit like how football has its hooligan element, but crown green bowls doesn't, yet.
 
I tried an Apple in John Lewis whilst shopping over Christmas and didn't see any advantage to what I already have with Windows 7. The graphics are certainly more animated, but it's a long while since the opening or closing of a file to a fanfare of effects lost its ability to keep me entertained, so if that's the appeal, I can do without. I also didn't find the buttonless mouse to be very tactile.
 
My better half was given a new Windows 7 laptop to use for work at home and it connects without delay to our Wi-Fi network and stays connected too. I enjoy a similar experience with the various systems we have around here as well.
 
Most importantly of all is that only one piece of software that I use daily is available on the Apple platform, which means it's a PC or nothing for me.
 
All the best.
 
Martin
 
Thread: Here we go - parting off
25/12/2011 01:58:51
My view is that it's important to try to understand why a jam up occurs.
If it only happens once you're some way into the cut, then I think it's pretty fair to say that the swarf that is being produced is somehow involved in the process - providing tool angles are roughly correct of course.
 
On the other hand, jam ups from the 'get-go' are more likely to be related to cutting tool geometry and/or rigidity/speed errors with the machine, as well as possibly inadequate workpiece mounting.
 
Therefore, replacable carbide tip tools almost alway work well when used with a good machine in the otherwise uncertain front toolpost position, because their geometry is tuned for chip shaping and ejection. I find that some kind of cutting fluid can also help too.
 
 
Martin.
Thread: Precision Levels - calibration
23/12/2011 18:32:40
Posted by Les Jones 1 on 23/12/2011 15:06:22:
...if my calculations are correct for a 6" length of tube the centre would need to be packed up about 12.5 tho to produce a 60 foot radius of curvature and from centre to end would show about 0.24 deg.
 
Les.
 
 
I wonder if we could be making our own precision levels?
Those figures sound like they might be within the bending tolerance of a piece of glass tube.
So it might be worthwhile for someone to set some tube on a frame and jack it up in the middle a few thou' to see if this could work.
 
Martin.
Thread: iPad in the workshop, something to bear in mind!
19/12/2011 18:29:33
Posted by Ian Hewson on 19/12/2011 18:16:11:
Hi Martin
Sorry, but I don't have the time to reply to that one, but try reading the thread on poor Windows problems.
Ian
 
There's no point in me doing that Ian, because Windows works well for me.
I was just hoping you could substantiate your remarks.
 
 
Martin.
19/12/2011 17:48:22
OK then Ian, I'll bite - what doesn't work in Windows?
 
 
Martin.
19/12/2011 17:26:44
Posted by Ian Hewson on 19/12/2011 16:54:14:
...Thought I had got on to another ""we hate Apple site, although we have never used one"
never mind though, I use and love Apple, gave up Windoze years ago.
Ian
 
 
I'm very happy with Windows too. It does everything I need, from music, video, photography, internet, DTP and CAD/CAM - you name and there's a huge range of programs to choose from including thousands of free ones.
 
No cost updates and bug fixes for the life of the product as well, so for around about £70 for the operating system, it seems like a pretty good deal to me.
 
What can Apple give me that is better?
 
 
Martin.
 
Edit: I also use it to control CNC lathes and milling machines etc.

Edited By blowlamp on 19/12/2011 17:36:35

Edited By blowlamp on 19/12/2011 17:39:37

Thread: Rotary table dividing Calculator
14/12/2011 17:15:02
I'm just glad that I didn't pay good money for a paranoid anti-virus application, when a perfectly decent one is available for nowt, otherwise I'd have missed this neat utiliy.
 
Thanks to John McN' for providing.
 
 
Martin.
14/12/2011 12:07:37
I downloaded the file from the second link and sent it here http://virusscan.jotti.org/ and here http://www.virustotal.com/ with nothing of any concern being found.
 
The file is working OK on my system and Microsoft Security Essentials is up to date as of this morning.
 
Martin.
14/12/2011 09:24:22
The second link is OK through Microsoft Security Essentials - maybe a false positive from Avast?
 
 
Martin.
Thread: Dead Smooth File
09/12/2011 22:03:30
 
 
Martin.
Thread: Chuck locking ring.
09/12/2011 14:17:42
Ian.
 
Remember that the ring will exert a magnified clamping force across the diameter of the flange by virtue of the fact that a reduction of the circumference will be multiplied by the function of pi.
 
So a change of 1 unit of the circumference (by tightening the clamp) divided by 3.142 equates to a theoretical change of 0.3182 units of diameter.
 
A kind of gearing or leverage effect is in action here and very little movement is required which is why - counterintuitively, it works.
 
 
Martin.
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