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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: Why is my silver steel undersize
19/01/2020 14:34:30

Printer rods are 7.92mm diameter so you are obviously reading those correctly.cheeky

Ian P

Thread: Laser Cutting Aluminium.
17/01/2020 23:02:20

Company is Anodisers Runcorn Ltd

Unsurprisingly its located in Runcorn, Cheshire

17/01/2020 21:42:44

This is the part I had waterjet cut before I sent it for anodising. I cleaned up the bore with a flap wheel (cylindrical type) but apart where I have machined the mounting surfaces its more or less as I received it.

The ovoid shaped bore is about 220mm wide

50mm spacer ring.jpg

17/01/2020 21:31:42
Posted by Chris123 on 17/01/2020 21:00:28:

Thanks, I´ve had aluminium water jet cut before, which was a very bad finish and bad taper.

It is all 6mm and 12mm thickness, I´m hoping to not have to machine edges on parts that fit together at 90 degree´s.

Find another waterjet cutting company!

I have just picked up a part cut from 2" thick 6082T6 and the taper was less than 1 degree. Over the 2" the taper size difference was about 0.5mm. It being anodised now otherwise would measure it.

Ian P

17/01/2020 20:53:16

Very little difference in finish or taper in my experience. Obviously varies with thickness and what the finished part is (ie depending on what you are making it may not even matter) but on 3mm ali a few strokes of draw filing is all I do (sometimes)

I would say that in general on thicker material (say 12mm) ali has a slightly better edge.

Speak to the company as they can alter the quality by changing the cutting speed and other parameters, better is slightly more expensive.

Ian P

Thread: Musings on taps
16/01/2020 21:48:39

The recent thread about 'driving taps' has prompted me to set out some other tap related matters that I have often wondered about. I could probably find answers to at least some of them if I used a search engine but I wondered if the things I have experienced have been seen by others.

'A'
Compared with the size range that (one example) of a typical bar type wrench can hold, I rarely find that the whole length of the squared end will enter far enough for the screw to bear somewhere near the middle, ie the squared section of the tap is to short (or the wrench too thick)

'B'
Plug taps with a 60 degree conical end are really not fit for purpose because they cannot really cut close to the bottom of a hole. Without tap re-sharpening facilities I just grind the point off.

'C'
If one breaks one of the first two serial taps, then presumably the whole set is compromised because, as far as I know, individual replacements are not sold.

'D'
Might be me, but I have not found any benefit in using serial taps. The tapping process take longer and is more of a faff and as far as I know it is less than ideal for cutting threads in tough materials. As I understand when cutting stainless steel is best to take a reasonably deep bite with the tap (say miss out the taper tap) so that whilst the cut is concentrated on fewer points, its better than multiple smaller cuts over the length of the taper tap.

'E'
When cutting a thread in material that is much shorter than the tap length I tend to let the tap pass almost as far as it will go (I tap under power at low speed with very limited torque) When reversing the tap out I find that when the tap is about half way disengaged the tap tightens up somewhat before then easing up and becoming as free to rotate as it was at the start of unscrewing. I see this with a whole range of thread and type and sizes but cannot fathom out what could cause it.

'F'
Despite the high quality and the 'ground all over' finish of some taps I have found some where the thread is off axis (even skewed) to the body, even with well known brands.

'G'
I'm just amazed that its possible to manufacture very small taps (like M2 and below) and incorporate the relief etc. The grinding wheels must be very small with even tinier features yet last long enough in a production environment.

Ian P

Thread: Cut a transverse tapered hole (Unimat milling column)
12/01/2020 21:26:12

Out of interest I dug out some of the cutters I have and measured the included angle of each cutter. All the proper ones are 20 degrees and the Chinese Ti coated one is 17 or 17.5 degrees. (largest one is 30mm)

All are a quite a way from the 1:2 taper Andy measured (so 28.03 degrees inclusive).

Jason's hand filed option is definitely the best suggestion, best too because it can be fine tuned with blue to get good contact withe the cotter.

Ian P

20200112_121148.jpg

11/01/2020 16:28:25
Posted by Andy Carlson on 11/01/2020 14:19:21:

Thanks folks. I do fancy the D bit option - it's something I've not done before and I'm usually happy to invest a bit of time if I'm learning something as well. I'll keep the RS cutter as plan 'B' if I can't make the D bit work.

Since the minimum diameter is quite big I'm thinking of extending the small end and putting in a centre drill so that I can support that end with the tailstock during the cut.

Fine tuning the shoulder position as the last op seems like a good plan although I think that roughing the spigot first will reduce the amount of metal for the 'D' bit to remove. I might also do some step drilling to further reduce the amount of work or am I over-thinking this?

Regards, Andy

Step drilling will definitely make it easier for the conical cutter. I just looked at the RS one suggested and its probably too small for this job if hole at the small end is about 10mm. I have collected an assortment of cone cutters so have a range of sizes (up to about 40mm) most of them are of cheap eastern origin but work as well as genuine conecut ones do.

I'm quite happy to loan you one (where are you?) as I think its a relatively lot of work to make a D bit.

Unless I misunderstood Michaels approach, I dont think a joint in a milling machine column is a good idea from a rigidity point of view.

I think Emco intended the shoulder where the column changes diameter to be the feature that in combination with a close diametrical fit, holds the column dead square to the base casting when it is pulled down tight by the wedging action.

Ian P

11/01/2020 12:57:43

I would go for the cone cut option to create the tapered hole in the column. Whilst they are intended to be used on sheet metal they do cut over the whole cutting edge so with care can be used to create the hole you need.

I would definitely do the cross drilling and tapered hole before reducing the column diameter. The 20mm spigot needs to be accurately on axis so hold the bar in a collet if it will pass through the headstock, or use a fixed steady with the 'top' end of the column set true in the 4 jaw.

Getting the position of the shoulder in the right place will be easier than putting the tapered hole in the right place if you turn the spigot first.

Ian P

Thread: Stuck Chuck
10/01/2020 11:22:48

I'm glad that Steve has solved his stuck adapter problem but there are two points I am not clear on.

What metal Is this 3 jaw chuck made from? I have a sneaking feeling its not the usual steel or cast iron.

Also I have not come across ANC threads, is that the same as UNC?

Ian P

07/01/2020 18:57:24

I have another thought on this stuck adapter.

Looking at the picture of the chuck that Jason posted, it appears that the hole in the face of the chuck is larger than the 3/4" thread, therefore I would assume that the adapter (if the threads were not binding) would pass right through.

If that is the case then there is no need to waste time unscrewing the adapter, what it really needs is 'tightening' from the back.

I'm not sure which way Steve has been turning the slotted end but if a 3/8" nut and a small diameter washer or two were put on the adapter it could then be rotated clockwise (looking at the back of the chuck) with virtually unlimited torque using a spanner on the nut and the chuck jaws held by any method.

Or have I missed the bleedin obvious?

Ian P

07/01/2020 18:42:49
Posted by Steve Crow on 07/01/2020 18:13:42:

Many thanks for all your suggestions and questions.

If that doesn't work Ill be fiilng some flats.

What wrong with using a well fitting screwdriver?

Ian P

07/01/2020 14:23:39

I did consider that the chuck thread might not run all the way through the chuck (it would be unusual though) but why the adapter would jam so tightly is a mystery. How tight it actually is something is depends on the person judging it and the method of applying the force. To anyone with a reasonable size vice on a strong bench, removing the adapter looks to be fairly easy, in Steve's case though he says he has a kitchen table workshop so just holding the vice and screwdriver in alignment whilst applying the turning force could be challenging.

Its not easy to see the state of the slot or the end of the screwdriver but neither look good. Not much can be done to improve the slot now that it is at the bottom of a recess, but the screwdriver looks quite rounded.

Unless the adapter to chuck thread has galled a good fitting screwdriver and some means of holding everything aligned should be all that is needed. I would think that the slot is potentially capable of imparting higher torque than anything gripping the short 3/8" thread.

Ian P

Thread: Anyone with a surface grinder near Leeds?
07/01/2020 12:02:28

We know small objects can be surfaced by moving them around in figure of eight pattern on wet and dry carborundum paper stuck to a flat surface.

Maybe you could use the same idea with your anvil by turning it upside down on a concrete road surface and then with a rope around its waist, tow it for few milesdevil

Ian P

Thread: Stuck Chuck
07/01/2020 11:38:18

Without wanting to take this thread off topic I am curious about the security of fastening a relatively large chuck to a rotary table by means of such a coarse small-ish diameter thread.

Quite rightly, on this and other forum there are frequent warnings about chucks becoming loose when a lathe is run in reverse. Surely the potential for a chuck held on a rotary table to come loose is (depending on the actual machining operation) is far greater.

The chuck in question looks to be ideal for attaching to a rotary table by clamps in the groove on perimeter of the chuck body, no worries then about it moving or stuck adapters.

Ian P

07/01/2020 11:25:08

I would still like to know why a headless screw can jam in the parallel (through?) thread of the chuck.

Ian P

07/01/2020 08:48:55

Thanks Michael, your link shows what that the adapter larger diameter thread fits the chuck body.

I now assume that the chuck thread has a shoulder or restriction (where the thread runs into the smaller tapping diameter) otherwise the adapter would pass right through the chuck body. If not what is it jammed against?

Ian P

06/01/2020 21:03:38

I am not familiar with Sherline lathes but it seems odd that its mandrel has a 3/8" UNC internal thread rather than the conventional male thread and register for the chuck/faceplate etc.

In any event does the screw with a slotted head actually have a shoulder at some point or does it just like a large grub screw that converts the UNC to the chuck thread?

I know the above does not solve the problem, but AIUI (or dont understand it) what it the screw stuck against?

Ian P

I missed the rotary table mention. Still not sure if there are two different threads on the adapter thing

Edited By Ian P on 06/01/2020 21:07:15

Thread: Correct use of slitting saw for deep cut.
30/12/2019 10:21:02

I think a clue to the problem was the 'pronounced dish' in the blade.

It sounds as if the arbor is not clamping the blade properly. I have seen slitting saw blades that were eccentric but never come across one that is not flat.

Ian P

Thread: Any real risks corrosion etc combining aluminium and steel
28/12/2019 15:42:30

Paul Kemp's reply says it all!

Until Chris TT addresses Paul's points I think its pointless offering advice and prolonging the agony as it were.

There are reason and places where two particular materials are best not combined so there is nothing wrong with Chris asking the question so we can offer advice in the right context.

Ian P

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