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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: Collet chuck for workholding on the mill
11/01/2021 19:38:46
Posted by Vic on 11/01/2021 19:24:24:
Posted by Ian P on 11/01/2021 13:33:50:
Accurately centering a block gripped in the vise can take time whereas allowing the job to self-centralise before tightening the clamps is near instant.

Ian P

With the vice already clamped it’s just a matter of moving the table until the fixed jaw just touches the collet block then nip up the vice. It’s very quick.

Fully follow and understand what you are saying, I use the same technique often, however its determining the point of 'just touches' that introduces uncertainty of position, whereas clamping only in a downwards direction (whether vise or a block) minimises any error.

Ian P

11/01/2021 19:30:06
Posted by Vic on 11/01/2021 19:18:55:

I’d use a similar method to that already mentioned but instead of having to position two clamps I’d just tighten the vice. I often use this sort of method and ensure I have lots of “pins” in different diameters.

There have been several methods mentioned in this thread so its not clear which one you are referring to, however when I put anything in a vice I just tighten it toowink

If the workpiece is already held on a pin in the mill spindle then its only safe to close the vice jaws if the vice is free to move, which is what the OP showed originally.

Ian P

11/01/2021 15:27:43

I think there is a big difference between large and small workpieces when using a self-alignnent technique.

Centralising (say) a 3mm diameter pin in a collet block already gripped in an unclamped heavy/bulky vice is not what I would call a sound method. I too dont use a key to locate the vice but once I clock it into position avoid moving it unless its absolutely essential. Since the DRO knows where the vice reference faces are it knows the position of the collet block axis (on the square block anyway, only one axis on the hex block).

Its debatable whether setting by DRO will be any better or worse than locating mechanically but I JH's method looks optimum for small components, just a pity that standard collet blocks dont have a deep groove at the 'bottom' end into which toe clamps could sit.

Ian P

11/01/2021 13:33:50
Posted by Vic on 11/01/2021 12:37:04:

Unless I’m missing something I think I’d just use a collet block in my vice?

I too use a block in the vice (although not everyone has them) but I can see a big advantage with the JH method.

Accurately centering a block gripped in the vise can take time whereas allowing the job to self-centralise before tightening the clamps is near instant.

Ian P

Thread: Boring a circular groove
29/12/2020 22:00:58
Posted by Emgee on 29/12/2020 21:39:15:
Posted by Chris TickTock on 29/12/2020 11:35:25:

Hi Guys, thanks for posts for clarity the half round groove goes right across the face in a straight line.

Regards

Chris

It's a bit OTT IMO to need a drawing of any kind to know what Chris wanted when he posted the above.

Emgee

Depends on what you mean by 'above'.

Chris supplied a drawing that was nearly as undecipherable as his question.

Ian P

29/12/2020 12:10:31
Posted by Chris TickTock on 29/12/2020 11:35:25:

Hi Guys, thanks for posts for clarity the half round groove goes right across the face in a straight line.

Regards

Chris

Chris

So if this is a half round groove running the whole width of the face, it odd that you asked about doing it by boring? Even odder that you had to ask at all thinking.

From your previous posts and work that you have shown or discussed its obvious that you are fairly well skilled and knowledgeable, my initial thought was that this groove was somehow in a difficult area to access.

I would like to respectfully ask that in future you take a little time composing your questions.

Ian P

28/12/2020 16:41:06

I wonder why I have that 'here we go again' feeling....

Many times previously, threads have developed a life of there own with many members suggesting solutions for problems the OP never even thought existed. Without knowing what Chris wants all we can go on is guesswork. I know I mentioned O-ring but TBH it was a bit tongue in cheek (O-rings are rarely or never fitted to semicircular grooves).

To me a groove is a groove. A stationary D-bit would work as a form tool but its an unlikely tool to use in the lathe or mill because most bit are relatively long so holding it would not be easy.

Ian P

28/12/2020 16:05:29
Posted by JasonB on 28/12/2020 15:45:03:

You could make a D bit or use a 2.5mm ball ended milling cutter, in both cases just plunge straight in.

That would create a circular (semicircular in section) depression, its not a shape I would describe as a groove as one would expect a groove to have a length dimension.

Ian P

28/12/2020 15:43:28

Happy Christmas

I think you will need to explain more clearly what you are trying to do.

Is this a circular groove in a face? (Say for an O-ring face seal)

'Bottom of cube' could be anything.

Ian P

Thread: Advice please - Brushless motors
22/12/2020 22:33:53

It certainly looks good for the money!

Hard to tell from the pictures what the motor is, I have seen hundreds of different brushless motors over the years but no examples of ones used in cordless power tools.

The listing first picture shows something that might be the motor (with what looks like a section picture of heavy duty cable! ) but its hard to reconcile that with the the other computer generated images that appear to show a fairly small diameter motor. Ballraces appear in one picture but maybe they are just for decoration. Does the charger come with a UK mains plug or if not is that the reason for the strategically placed bit of white cloth.

I'm still tempted to get one though!

Ian P

 

Edit, White cloth is gloves!

Edited By Ian P on 22/12/2020 22:35:12

22/12/2020 20:50:08

When there is a motor controlled by electronics there is little difference on cost whether the speed is set by a potentiometer or a multiposition switch.

'Ring of magnets around a set of coils' hints of it being an external rotor motor (often with silly description of being an 'Outrunner' similar to the type used in model aircraft. Motor speed is controlled by changing the commutation frequency.

What make and model is it, also the one Ady mentioned withe the very high tourque?

Ian P

Thread: Drilling then Tapping in Drill Press
05/12/2020 10:36:53

As others have said ditch the spring loaded widget and use the chuck.

I am fortunate in having a VFD on my Fobco. I set it up so the lowest frequency is 4Hz at which speed it has little torque but I use it for tapping (with the tap in the chuck) from M2 upwards. (I have fingertip reverse switch) I frequently tap scores of 1/4" and 3/8" UNC in 10mm ali plates not clamped down so it aligns itself to the tap.

Ian P

Thread: Slot drill hole size?
26/11/2020 16:13:16

Hole with flat bottom, why not just use a flat bottom drill?

Seems to be a standard engineering cutting tool, one suggested use is starting a hole on a curved surface (not with a pistol drill I hope!).

Link below is to a carbide one but presumably HSS are made

Flat Bottom Drill

Ian P

Thread: Lathe improvements?
25/11/2020 11:39:05
Posted by Matt Harrington on 25/11/2020 09:31:01:

"...This is a _model_engineering_ forum, the whole raison d'etre of which is to "waste" time and money..."

Andy, never a truer word.....

Matt

What a strange outlook!

Despite the title this is not just a forum for model engineers, who I am sure do not all waste time and money.

There are many avid user of this forum that have no interest on models or steam.

Ian P

24/11/2020 15:12:19

That certainly looks a substantial spindle assembly. Presume you have access to a large lathe and other engineering facilities to braze and machine a spindle of that size. (machined after brazing?)

I agree about the vulnerability of screwed on chucks but having gone to the trouble you have, why not elect for camlock mount?

Ian P

Thread: Beginner milling chuck key question
20/11/2020 14:40:14

I've never crossdrilled chuck keys but usually fitted a grubscrew axially into the main bar which already has a centre holes from turning operations. A dimple in the cross bar and jobs a good-un

Ian P

Thread: Machining Ball Screws Accurately
17/11/2020 20:53:22
Posted by DC31k on 17/11/2020 20:48:39:
Posted by Kiwi Bloke on 17/11/2020 20:15:50:

So, balls in the thread, sleeve outside and sleeve held in 4-jaw? But getting the sleeve ID correct means measuring over (3) balls in the thread, which is awkward.

Is there any opportunity to develop this method and use soft jaws, each jaw counterbored for one or more balls of the correct diameter to suit the screw, with the counterbores spaced at 1/3, 1/4 or 1/6 of the thread pitch apart to suit number of jaws and 1 pitch apart if multiple balls per jaw?

Especially with a 4 jaw independent chuck, you would be gripping on the thread's pitch diameter and could then dial in concentricity in the normal manner.

Its the last sentence that is the problem, See Joe's post about clocking

Thread: Whitworth v UNC
17/11/2020 20:48:49

3/8"x16 is a thread size that has become standard in the film and video industry (as has 1/4x20).

I know there is an ISO standard for the 1/4" thread (probably one too for the 3/8" so all camera and grip equipment have male and female threads that work with legacy UNC and Whitworth kit.

Must add though that these fixings are mostly hand tightened and not under great stress.

Ian P

Edited by punching that smiley up its bracket

 

Edited By Ian P on 17/11/2020 20:50:12

Thread: Machining flats on bar stock
17/11/2020 20:35:35

I did a similar thing on a 20mm diameter bar 1.8m long. I used a precision level (clamped to the first machined flat) as a reference. I have (temporarily) forgotten how I allowed for the milling machine not being precisely level but as its not bolted down I made sure it did not move between operations.

IanP

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

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