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Member postings for Ian P

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

Thread: DC motor reversing
17/07/2020 21:04:17

If its a DC motor, which ever way round you connect it to a DC supply it would not buzz so there must be some AC present.

With brushed DC motor, reversing the connections to the brushes will reverse the motor. I do not think that the blue and brown wires you show go direct to the brushes of the motor

The two connections to the motor might be brown and blue but they are not live and neutral, if the unit operates on a DC supply then they will just be positive and negative

If the blue object on the PCB is a relay then that might be the device that actually reverses the connections to the motor.

More investigation needed, is there any label on the motor?

Ian P

Thread: Jig for hand tapping
16/07/2020 18:06:33

I rarely tap with conventional tap wrench.

You probably already have a 'suitable jig' in your workshop. Mine is my pillar drill (for work not in the mill or on the lathe). Depending on thread size either hold the tap in the chuck or make a tubular extension for you tap wrench.

Turn the tap by gripping the chuck.

I would say that 80% of holes I tap (M2 to M12) in the drill chuck are under power or more correctly power assistance. VFD at lowest frequency and lowest torque.

Ian P

Thread: Leadscrew suppliers
14/07/2020 11:43:44

My comments about wear were triggered by Michael G's mention that a long nut setup would have 'comparatively rapid' wear.

What I said earlier about backlash was mainly referring to positional error, slide friction or sticktion has always been (on my machines) enough to overcome the climb cutting forces. Maybe I have my gibs set to tight?

Ian P

13/07/2020 22:33:24
Posted by Michael Gilligan on 13/07/2020 21:37:31:
Posted by Len Morris 2 on 13/07/2020 21:21:25:

Good comment Ian. […]

.

Agreed yes

The only caveat being that both the long nut and the screw will wear comparatively rapidly, if they are busy averaging-out all those variations.

... Still a good bargain-price solution though !

MichaelG.

I've just been trying to think about the wear aspect..

Small nut, wears more than the leadscrew. Make the nut longer and its lasts longer (more metal to wear away) but presumably wears the leadscrew by taking the highs of the threads that are out of pitch relative to the average pitch. Once the screw high spots are worn away, the lead of the screw becomes a more consistent pitch.

No idea if this is what really happens but I have a vague memory of Joseph Whitworth using long nuts on early metrology equipment.

Ian P

13/07/2020 21:59:56
Posted by Len Morris 2 on 13/07/2020 21:21:25:

Good comment Ian. My nut is some 40 mm long. There wasn't room to put anything longer under the table. Once made it was bored out 10 though, split on one side and adjusted onto the threaded rod by 3 cap screws to get rid of backlash. Works fine but again, it is commercial threaded bar and I wouldn't pretend it's as accurate as a proper ground lead screw. Wish I could afford a DRO !

I would say that igaging or igaging type of DRO's are pretty affordable and the accuracy is adequate (same technology as digital calipers) so ideal for budget home engineering where you are making parts to fit each other rather than to volume production interchangeability. Backlash and feedscrew errors become almost unimportant

Ian P

13/07/2020 20:17:27

My take would be that on a manual mill (ideally with DRO) if you use bog standard threaded rod the pitch accuracy can be 'improved' by having a much longer nut that engages over a high number of threads. I was told (yonks ago) that this averages out pitch changes and helps reduce backlash.

Ian P

Thread: Coronavirus
09/07/2020 22:27:04

I dont think anyone here can tell you where you posted first, but it does not look as if it was on this forum.

Also not the optimum forum for medical discussions.

Ian P

Thread: Laser DRO sensor
09/07/2020 14:41:14

I know this is prolonging this off-topic discussion, but is the rear 'post' bolted straight down to the cross slide or does it in some way locate on the side dovetails?

Either way the cylinder block looks a lovely bit of work.

After seeing yours, I must make a swarf tray to fit between the ways, one thing that I noticed when I changed from a Boxford lathe was that cleaning up (or finding dropped parts!) was much more of a pain.

I dont have any microbit tooling but its nice stuff.

Ian P

09/07/2020 12:56:40

I didn't know the M300 had a dovetailed edge, are there some accessories that use it?

That Newall installation looks good.

I see your cross slide also has tapped holes, the ones on my M250 seem to be in mostly random positions and none really line up with counterbored holes in the (still unused) tee slotted milling table that came with the lathe.

Ian P

09/07/2020 12:13:28

The scale is the magnetic one from Machine DRO

Tapped holes filled with button head screws came with the lathe (Harrison M250) I assume they are not original

Ian P

cross slide dro scale .jpg

09/07/2020 11:46:27

I know its only my opinion but that does not look like 'minimal' interference with the tailstock, it also looks extremely vulnerable by being bumped into by the tailstock.

At a guess it looks like 30mm or so of lost tailstock travel towards the carriage. I have a much larger lathe and the magnetic scale mounted in the same place as yours only adds 10mm to the carriage width. and its more or less solid ali extrusion so does not mind being hit by a heavy tailstock.

Ian P

Thread: VFD/Lathe fault
09/07/2020 11:34:58

Did the procedure in the guide cover the same information that was suggested in the replies in this thread?

Whether it did or not, purely on a 'dont need to know' basis, I and others would like to know what the actual cause was?

Ian P

Thread: Upload photos - canít identify which one
04/07/2020 17:22:38
Posted by Michael Gilligan on 04/07/2020 11:53:49:
Posted by Paul Lousick on 04/07/2020 11:24:07:

Michael,

I have just checked the link to your photos in MEW and they all appear as photos.

Paul

.

Paul smiley

The point is not whether or not they are photos ... it’s the ridiculous hexadecimal file-names: You may need to click on them to see the names.

The two bird pellet ones, and a couple more, have friendly names because they were uploaded from the Mac ... the others have hex filenames that are mysteriously allocated by the iPad [but are not used if, for example, I attach them to an eMail]

MichaelG.

.

’ere we go

902ba8af-d2f5-4741-a35d-4af62e645951.jpeg

Edited By Michael Gilligan on 04/07/2020 12:07:36

Only indirectly related to the jpeg naming problems on this forum but when you say 'attach' to emails (emboldened above), do you meant attached or do you mean embedded?

When I receive emails from Mac users they usually come embedded and as I use Outlook (not the latest version) the image is only really viewable if I save them first because they open in the email much bigger the will fit on the screen, yes I can pan up/down and side to side but there is no zoom, hence saving and viewing in another program.

Some Apple used do send me images as attachments which is fine. Presumably the Apple default is to embed?

Ian P

03/07/2020 23:10:45

I rename the files before I upload them.

Ian P

Thread: Lathe dogs
03/07/2020 19:13:38

I no longer have any lathe dogs as I found they never fitted or suited the things that I turned between centres.

Depending of what the job is I use toolmakers clamps or some other device like a shaft collar. When working on say, a large diameter thin (ish) wall tube with bungs in each end, I would just use duct tape to pick up the drive from the chuck body (with freshly turned centre).

Unless you know you are going to be doing work that will always fit in a dog, save your money for something else, or until you need them.

Ian P

Thread: Epoxy & Steel
03/07/2020 18:52:38
Posted by JasonB on 03/07/2020 11:19:16:

The very fine aluminium powders will give you close to a steel look when sanded and polished, you need to put as much powder into the epoxy as you can. This bowl was filled with it.

JBWeld which contains metal will dry dark grey and is hard to tell from emery cloth finished cast iron.

On seeing the picture, my first thought was that it is not surprising the bowl is empty, its got holes in it! (well you did say it was filled with powder and epoxy) I now see the filler is almost the same colour as the background (could be my monitor though)

Ian P

Thread: What a silly Vee block this one is!
02/07/2020 16:26:29
Posted by Emgee on 02/07/2020 12:56:24:

Ian

You say both blocks are ground to the same angle but do they match if 1 block is turned by 180 deg, ? if they match perfectly which ever way the pair are used it means that both sides of the V are ground to the same angle, rather than 1 side ground 47 and the other side 45 for your estimated 92 degrees.
If the sides are ground at different angles you cannot set-up by clocking between the V surfaces to find the centre.

Emgee

I only have the one block, what I meant was that both sides of this block have ths same included angle.

My guess at 2 degrees was way off. I have just measured the angle using a (presumably pretty accurately square) gauge block and feeler gauges and its nearer to half a degree. So what I would expect to be 90 degrees is nearer 90.5 degrees.

I do have some pairs of Vee blocks and each pair have matching numbers on them, presumably matched pairs.

Whilst this wonky one has no identification marks, the quality of the grinding examined closely with a strong magnifying glass looks better than an Eclipse pair which claim to be to toolmaking standards (whatever that may be).

I know these blocks are primarily for holding round stock but its not their only purpose.

Ian P

02/07/2020 12:16:33

I am sure it a manufactured product although I cannot see any identifications marks, it is ground all over and it is really hard steel, I doubt it was an apprentice piece.

Its not easy (for me) to measure the V angle but I estimate its only 1 or 2 degrees greater than 90. Both the Vee's are the same angle too.

Ian p

02/07/2020 11:21:15

I bought this single V block many years ago at a steam rally. It has been on my bench and frequently used on the drilling machine (mostly) for free hand cross drilling but also for many other tasks. Not being is as new condition its been used as a hammer, as packing in the milling machine and lots of other non precision tasks. Its about 1.5" square and 3" long.

I discovered early on that the relief channel at the bottom of the vee is not deep enough to accept a rectangular object and often though of just using an angle grinder freehand to deepen it, but have never got round to it.

Yesterday I was making a right angle optical device which has a mirror at 45 degrees in a block of aluminium. I sat the part machined item in the V (it had a big chamfer so did not touch the bottom) and found that it did not make full contact with the V faces as if the cube shaped part part I had made was not truly square. After a few moments investigation I found that the V was not a true 90 degrees but more like 92 degrees!

Why would a manufacturer make a vee block at anything other than 90 degrees?

I'm amazed that I have had it so long and never noticed this 'feature' before!

Ian P

silly v block.jpg

Thread: Installing a magnetic DRO on my VM32L
02/07/2020 10:19:18

Really crude sketch of what I was trying to suggest earlier.

Something like 3/4" x 3/4" x 1/8" aluminium channel will be 1/2" wide internally which I think will be wider than the sensor head.

I have shown the channel sticking out at the back of the machine only to show that once you know the overall length of channel required it can be positioned offset towards the rear so that the rear end of the extrusion projects no further than the back of the machine base.

Hope that makes sense

Ian P

scale mounting.jpg

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