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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: Machining Ball Screws Accurately
17/11/2020 20:24:37

Its something I have often wondered about even when machining normal threads.

The true centreline (axis) of a cut or rolled thread is not always concentric with the crests. I dont know whether that applies to ball screw threads but for best accuracy it would seem best to devise a way of using the ball track as the reference.

One way of getting threads concentric is to wind a suitable gauge of wire into the thread before putting it in the chuck so the jaws grip the OD of the wires which in turn are sitting on the thread flanks. Ballscrews would need mighty thick wire to do the same trick so,

What about having a thin sleeve long enough to contain a string of balls over several thread pitches and then pressing the screw with sleeve and balls fitted into a freshly bored hole in the lathe. Would need a dog to drive the screw.

Ian P

 

Slow typing on my part

Edited By Ian P on 17/11/2020 20:25:32

Thread: Bushnell camera problem
16/11/2020 15:54:11

The battery mentioned earlier was was for memory retention. the trap itself has a bunch of AA cells (not visible in the pictures)

Ian P

16/11/2020 13:59:14

I've repaired and modified several different trailcam's and although none identical to yours I would say 100% that it does not have a battery for the memory that retains the settings.

Like you I dont like to accept that some devices are throw away but probably even the manufacturer (or the factory making the PCB) would scrap it if it failed tests before it was even assembled into the product. It would only be re-worked if the fault was minor or the component cost warranted it.

One think worth trying (if the zebra strip solutions above dont work) is to minutely examine every component and soldered joint to see if the fault is visible. Surprising as in may seem the fault may not be electronic (as in a failed IC or faulty resistor) but may be 'mechanical'.

By mechanical I mean dry joints, cracked track, oxidised contact surface, connector contacts not making good contact because the plastic housing has distorted. A few minutes work examining a faulty piece of equipment can point to the likely fault even without connecting it to a power supply, traces of leaked electrolyte or even slightly discoloured resistors can be big giveaways. Not likely to be anything overheated in a battery trailcam but high humidity or dampness has killed several that I have seen.

Ian P

Thread: Who is Right?
15/11/2020 13:46:45
Posted by SillyOldDuffer on 15/11/2020 12:45:53:
Posted by Peter G. Shaw on 15/11/2020 11:40:35:

... I realised that the (secondary?) thread title did indeed mention lead-acid, hence I was wrong. That's all it was.

...

Peter G. Shaw

Well spotted - I missed that information, and it makes all the difference!

Almost invisible thread sub-titles should be listed as a software flaw in Lee's 'Archiac Forum' thread!

Dave

I too missed that.

I read through the whole post again before I sent my last post looking to see if the OP had stated the battery technology. I never saw the sub title.

I have fallen into the same trap before, so yes it is another item on Lee's list. Might be easier to deal with as its something to remove completely, I don't really see the purpose of a sub title.

Ian

15/11/2020 11:27:17
Posted by Peter G. Shaw on 15/11/2020 10:37:43:

Deleted.

Edited By Peter G. Shaw on 15/11/2020 10:38:32

Now I am even more curious. We have replies and suggestions so far based presumably on guess work. Pete's reply which he has now deleted summed up what I was thinking. Why delete it Peter?

I made a guess at method C because the OP's question being unanswerable.

Ian P

14/11/2020 20:41:12

Method C?

Thread: Is this better than single purpose rope?
12/11/2020 12:42:52

Only posting this because this product could be used for model engineering.

More than ordinary rope

I have no connection with the company and this is not an endorsement of their products.

Multi Function!!!!

Ian P

Thread: Delay to Issue 299
12/11/2020 12:31:50
Posted by Neil Wyatt on 12/11/2020 12:29:29:
Posted by Bazyle on 09/11/2020 18:09:23:

"Familliar faces". hum. After seeing someone purporting to be you on the zoom call I was left thinking ' can't be him - no hat'. And you didn't look like your previous avatar either surprise

Just thought. Maybe the avatar is some guitar playing hero of yours I'm expected to recognise?

Err... it's a picture of me with a hat on... they are removable you know 🤣

Neil

Removable

Hats or pictures?

Thread: CNC Lathe Scratch Build
06/11/2020 14:24:26
Posted by mgnbuk on 06/11/2020 13:34:44:

Timing belts are backlash free & the standard drive used for spindle encoders on smaller industrial CNC lathes. Larger lathes tend to use gearing inside the headstock, as the timing belt pulleys get to be too large diameter on larger spindles.

Nigel B.

I presume you are referring her to belt driving the encoder only?

A timing belt will have very low backlash especially as the encoder will have little inertia.

Ian P

Thread: Beginner milling chuck key question
04/11/2020 13:41:36

I wrote the following early this morning but got diverted before posting so see that Chris has used what I think is the most straightforward way of cutting the square end. Its still relevant though since his key is only 1/4" square and he is staring with quite large stock

Ian P

-----------------------------------------------------------------------------------------------------------------------

The part in question is only a chuck key but I am totally with Chris's philosophy of making a tool that looks and feels right. Some of the lathe chuck keys I have acquired or seen over the years are abominations and look to have been supplied by the manufacturer just so the chuck can be supplied 'complete'. I would post pictures of some that came with chucks I bought but every one I still have no longer look anything like they when I got them! As an example, a four jaw chuck key 9mm AF had been made out of 18mm diameter stock and only about 60mm long overall. Most but not all, supplied keys were made from parallel bar and only some had the bar waisted down between the handle and the square drive end. I have reshaped the keys to bulk reduce weight,

The optimum method for making this sort of chuck key would be by forging (followed by grinding if one were a perfectionist). For all practical purposes a key made by milling, filing, chiselling, grinding or any other method to achieve the required shape and size will do the job and work as a chuck key.

03/11/2020 13:41:26

Too late to edit my last post, but confess I replied without properly reading Bazyle's reply which had already covered what I suggested.

Ian P

03/11/2020 13:29:41

Since you mention holding the work in a square collet block withe the barstock horizontal, why not re-think the relative position of the job to the cutter. I would use the side of an endmill to cut the flats on the 'side' of the work rather than using the endface of the cutter.

The cylindrical shape of the cutter will produce a radius rather than a chamfer, its arguably better from a strength POV but I prefer the appearance anyway.

Ian P

Thread: Overrating a power supply for a DC motor?
22/10/2020 22:58:51

Bit of a mixture there. Motors are not usually 'rated' by current. 24V 200" is about 8 Amps but as you say the current drawn depends on load but many many other factors are involved.

The highest current the motor can draw is when it is stalled, You can work that out if you know the applied voltage and the resistance of the windings. When the motor is switched on from stationary (even without a load) it will momentarily draw a relatively high current (relative to its running current). Depending on what the motor is driving and what type of power supply is used this high initial current may have to be allowed for, a switch mode PSU which otherwise might be more than capable of operating the motor and its load not even get started properly as it may think its output is shorted.

A little more information is needed to be able to suggest an appropriate PSU.

Ian P

Thread: guideway surfaces regrind
13/10/2020 23:19:54

May or may not be relevant but I made the mistake of thinking the faces of typical engineering Vee blocks were a 90 degree included angle.

Your guides might be 45 degrees but the exact numerical angle value is not critical for operation so if you do regrind best to check first.

Ian P

13/10/2020 23:10:27

Regrinding the whole face seems a bit OTT as there is only line contact. Why not get bigger or smaller balls?

OK, I dont know the the construction but I would have thought smaller balls and packing to correct the height should be doable.

Ian P

I made the mistake of replying before reading your whole posting and seeing the the oversize ball bit. I was thinking of a change of ball diameter sufficient to move the running area away from the worn track

Edited By Ian P on 13/10/2020 23:15:26

Thread: FC3 'disposable' cutters in ER Collet?
10/10/2020 17:40:35

Sadly the spindle has no through hole so no drawbar options.

I could use a straight shank to ER11 extender, I would want to shorten the shaft and it would be more flexible solution in that it would hold a wide range of small diameter cutters and drills rather than just whatever solid ER25 shaped FC3 adapters I made.

I have just seen a '16mm Straight Shank (Plain) ER11 Floating Tool Holder for ER Collets' on the Cutwel site, The device in the picture looks the part, but I can see no description of what the 'floating' bit is.

Ian P

09/10/2020 20:53:45

Some of my ER25 collets (a mixture of cheap Asian and some quality european ones) have bores like your example but there does not seem to be a particular diameter value where the bore changes between the two types. Bothe my 6mm collets have full length bores.

The overall diameter of an ER25 nut and its closeness to the job surface with an FC3 fully gripped is still a limiting factor.

Ian P

09/10/2020 19:32:27

I have two 6mm ER25 collets but the parallel part of the FC3 cutters is awfully short compared to the length of the a standard ER25 bore so only a short part of the collet grip length would be in engagement which I understood to bad for the collet.

The other factor is that the diameter of the collet nut restricts how close one can mill near any obstruction. For fairly small cutter diameters (less than 2mm) I can hold the cutter in the Albrecht drill chuck (very low loads in plastic or non ferrous)

I could make my own 'solid' un-split collet replica's but as the auto-extract would not work I think I could revert to a external circlip but then I'm not sure whether a ball bearing nut would like that.

Ian P

09/10/2020 17:19:05

My Emco Mentor mill, has a non standard spindle and now has an integral ER25 collet holder, ie the female ER taper is the only means of attaching tooling.

I have about 10 collets with nuts that handle 95% of what I need (also have modified boring bar and drill chucks) but no good way of holding Weldon or the very short FC3 type cutters.

Ideally a ready made 'solid' collet with a grub screw would be good, does anyone know if such a thing exists? (say ER25 to 6mm)

I suppose I could always make plain steel blanks and drill/ream in situ, that way the projected length could be increased so the cutter is further away from the bulk of the nut.

Ian P

 

Edited By Ian P on 09/10/2020 17:19:23

Thread: capacitance in long cables
03/10/2020 12:38:05

I read this thread originally, but I have not had time just now to read through it to see if the point I am asking now has already been covered.

Isn't the problem caused in the first place by hanging long lengths of wiring directly on the logic inputs of the chip itself?

Normal practice is to have galvanic isolation (say with opto-isolators), Do you have anything in your layout?

Ian P

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