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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.

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Thread: Digital Readouts
05/02/2012 21:54:14
I wasn't complaining about the accuracy. My post was just to point out the fact that they are what they are, and not to expect silk purse quality.
 
I would love to have proper scales (glass, balls in a tube, or whatever) but I just do not have the budget.
 
The igaging ones, even at the higher eBay cost, are still good value for money.
 
Jon, What do you refer to when you mentioned movement?
 
Ian P

Edited By Ian P on 05/02/2012 21:55:38

05/02/2012 20:16:22
I wanted to by some of these scales and rang ArcEuro as the website showed them as out of stock. They told me that they expect to have them again in March.
 
I bought two off eBay which arrived yesterday. Easy to fit, I put them on my Emco mill in a couple of hours although I still have to put some form of covers over them to keep swarf out.
 
You need to be realistic with your expectations of accuracy. They are based on the same technology as used in the ubiquitous Chinese calipers (which I find perform better than their published specs) but these igaging scales are aimed at woodworking machinery which is why the 'seals' are only intended to keep out dust.
 
I have only done a very rough and ready check on the X axis scale and compared the digital value with the handwheel graduations. I got no discernible error over short distances but over the total travel of the table (400mm) there is a 0.4mm difference! Until I investigate further I don't know the cause so it might even be the leadscrew.
 
 
Ian P
 
 
 
Thread: Mystery Tooling
04/02/2012 20:48:22
Andrew
 
I too would be interested in buying a few of these (metric) taps if you decide not to keep them all.
 
Regards
 
Ian P
Thread: Brazed tip screwcutting. Tip radius, for what pitch question?
03/02/2012 19:10:24
Clive
 
Some manufacturers tip holders are definitely handed (helix angle wise) so in addition to internal and external the range of tooling is immense. The business corner of these triangular tips is on the left or right depending on whether its for internal or external use but I was not thinking of that when I mentioned LH/RH.
 
 
Ian P
 
 
 
 
03/02/2012 15:08:45
David
 
I had seen the MSC notes on screwcutting a while ago and it is a good guide. Greenwood mention the shims but do not show or price them on the website but having just seen the prices of their tips I can imagine the shims are really expensive,
 
I ordered some ER and NR16 tips from APT in Glasgow and they were under £5 each. To my eye they look OK but the proof will be when I use them.
 
On the Greenwood site it easy to see how the insert is tilted quite a bit (to give the correct top rake?). The loose shims must then have a sideways tilt to suit the pitch. I get the impression that toolholders have an inherent tilt for pitch which is why they are designated to cut LH or RH threads. To me it would seem logical to supply the holder with no tilt for pitch but maybe thats not good for business!
 
Ian P
03/02/2012 08:38:00
Posted by Ian S C on 03/02/2012 07:10:35:
Unless its a particulary dificult material, ie., a high grade steel, or stainless, I would tend to stick to HSS. No great problems with grinding up a tool, and making a boring bar to suit. You can use HSS square, but for internal tools, old center drills, or broken HSS taps, or old warn out end mills are ideal. Ian S C
 
 
The male thread is 48mm diameter and 3mm pitch on EN24T. I have ordered a brazed tip tool and will titivate the radius with a stone and magnifying glass. I am hoping to cut the LH and RH threads with the same tool.
 
I am doing the same for the internal threads in aluminium, carbide is not ideal so may make one in HSS which I've done before but in much finer pitches.
 
I have also bought internal and external ready profiled carbide tips of the correct pitch and will investigate making my own holders.
 
Ian P
Thread: Suggestions please Vol3
02/02/2012 19:28:44
Graham
 
I have followed this thread since the beginning and I do now have a better understanding of what you are trying to achieve. What I am unclear about though is why setting a handwheel index collar to a certain point is any different to turning the handwheel and stopping when a digital display reaches a certain value.
 
I am a total layman in regards to any medical matters and obviously do not know any details of your health problem but I do not see why you have to oscillate to and fro to get to a particular setting. With a normal graduated collar and leadscrew arrangement its usually preferable to approach the target stopping point slowly and in one direction (to account for backlash). There is no reason why the same technique cannot be used with a digital display.
 
I can envisage that the DRO on the Bridgeport you mention has far greater resolution than is required. Can I respectfully suggest that some of the least significant digits are obscured so that the display only shows increments of 0.01mm, I'm sure its worth a try.
 
Ian P
Thread: Stepper Motor Cable Length
31/01/2012 21:55:49
Jason
 
Your motors are superb, but making use of them might not be plain sailing!
 
The manufacturers of servo motors and drives are generally not helpful to individuals, data is hard to get hold of and frequently you need to buy their software just to configure them.
 
I have a beautifully made servo drive unit which I bought on eBay. The manufacturers want £900 to swap the input module (a tiny PCB)! and configure the drive to suit the model of motor I have.
 
If you can find some way of making them work with easily available NC software I will be impressed. I have a USB to canbus adapter, trouble is there are lots of different Canbus standards and you need to be conversant with programming to make any sort of progress. I don't want to pour cold water on your ideas but I imagine it will be tough going.
 
Ian
31/01/2012 21:06:47
Jason
 
What do these motors look like? what make are they?
 
20,000 steps is an awful lot for a stepper motor, I dont think I've ever heard of that before.
 
Maybe it has an encoder with that resolution, but to me they sound like servo motors.
 
Are you saynig the motor has built in electronics that takes a CAN bus signal?
 
Ian P
Thread: Suggestions please Vol3
30/01/2012 20:20:12
Graham
 
Unless I have completely misunderstood your requirement what you are requesting/suggesting would be almost as complicated/expensive as a DRO with scales but have none of the advantages.
 
It would be fairly simple to fit a rotary encoder connected to a digital up/down counter to the leadscrews but it would need an encoder disk with at least twice as many increments as the standard dial just to get the same resolution. By the time backlash has been taken into account what you would end up with would not be very accurate.
 
I doubt you have zero electronic skills! but none would be needed anyway to fit a ready made DRO system. There are some simple ones these days and if you are happy with totally separate displays for each axis why not consider fitting the 'igaging' scales (Arc Euro have them). From the description they would need some extra encasing to stop swarf getting in, but for their accuracy they are very cheap, its similar to the very common Chinese calipers so not what you would call traceable standards but they are reasonably repeatable so fine for ME use rather than commercial production.
 
Ian P
 
 
Thread: Brazed tip screwcutting. Tip radius, for what pitch question?
30/01/2012 18:41:56
I called a company today (in Glasgow) that has indexable holders and tips that seemed very competitively priced. I explained I wanted to cut RH and LH inside and outside threads. The person I spoke to was very knowledgeable and did not try to sell me anything, in fact he recommended I by brazed tip tooling!
 
I found out that the holders to cut LH and RH are different and need different tips. We discussed 'laydown' tooling and how 'shims' are needed to tilt the carbide insert. All in all it seemed to get quite involved. I doubt I will need to cut threads like these very often so dint want to invest a fortune in tools that wont get much use.
 
Clive,
I do understand your explanation. I want the male thread to be right (and look right) and conform to the ISO standard for M48x3, not having a test gauge or anything of that thread the ready profiled tips do appeal.
 
David,
I can see me getting the Chronos kits (but not necessarily for this job) which look incredible value. I presume they are only for RH threads though but it does not state it on their website.
 
Chris,
I have only ever used the cross slide for feed and had no problem so will do the same again.
 
Ian
30/01/2012 15:10:57
I need to cut internal and external LH and RH threads and was considering using ready ground indexable tips until I investigated how many tips and holders I would actually need, too many! so gets very expensive. Since I am unlikely to have an ongoing requirement I am now looking at using brazed tip tools.
 
I do not have the skill to grind the correct profile but several suppliers have 60 degree tools in their catalogues but I presume I will have to create the tip radius to suit the intended pitch?
 
In my case I want to cut a 3mm pitch threads but I suppose the tools when new are supplied with the tip left as a sharp point? Once radiused to suit a specific pitch the tool then becomes dedicated to that pitch unless it is reground?
 
Is my understanding correct? Buying one internal and one external brazed tip tools is a small fraction of the cost of indexable tools.
 
Ian Phillips

Edited By Ian P on 30/01/2012 15:11:27

Thread: Milling a semicircular groove, ball ended cutter, or?
25/01/2012 17:57:42
Peter

It might be just a thought to you, to me it's Brilliant!!!

Now you have pointed it out, it seems so obvious that I must have been asleep not to realise that the sacrificial metal I was put on to drill, was the same size as what I had just machined off!

Ian P
25/01/2012 16:12:36
John
 
Yes, I can cut the thread from the shoulder, its slightly more complicated because there are two versions I need, with LH and RH threads, also I would prefer to buy ready made carbide tips with full thread form. I am not sure how many holders and tip types I would need in total though, it might get expensive!
 
My chuck is just a screw on (Boxford AUD) so whilst I have screwcut in reverse before now I would not risk it now especially in EN24T at 45mm diameter.
 
Ian P
25/01/2012 14:04:04
With the benefit of all the advice and guidance given by forum members I have changed the design to something a bit more sensible.
 
I no longer intend to cut the grooves in the threaded section (which solves the problem of which to cut first) by putting the grooves in a reduced diameter section that engages with the stepped bore of the nut.
 
The only downside of this method is that the internal thread will have to be screwcut up to a shoulder, this is where an ELS or Grahams ingenious device would come in handy!
 
I will need to mill the groves in the EN24T with a ball ended cutter but I will make them as short as they can be and take my time probably with a carbide or coated HSS bit. I might rough out the grooves by drilling holes with a sacrificial ring of EN24T fitted, finishing with a ball ended cutter for size and appearance.
 
Ian P
23/01/2012 15:13:23
Hopefully the locking device will never actually be needed, its just an extra insurance,
 
These wheels sit against a flat flange which has five locating pegs that mate with holes in the wheel. The back face and the nut clamping face of the wheel are both flat.
 
I too have seen racing car chassis components and as you say they are an extremely light weight designed and made to aerospace standards. F1 and other top end racing cars have very sophisticated arrangements to hold the wheels on to allow very fast wheel changes. Some of the club racing cars though that just have a plain central nut to hold the wheel on have the hub cross drilled to take an 'R' shaped wire clip. Its there as a precaution which is all intend mine to be, but much less unsightly.
 
I have reread you post but I'm not sure which type of cutter did you thought was going to be the most cost effective.
 
Ian P
23/01/2012 11:08:18
Posted by GRAHAM Meek on 22/01/2012 18:59:03:
Hi Ian,
 
I would not expect a very high life from a ball ended cutter in HSS, solid carbide might be a better option or even TiCN coated HSS would give you longer cutter life.
 
If I were doing the job I would prefer to use something like a Woodruff cutter but with a radius on the periphery to match your loose fitting dowel, again coated if at all possible.
 
In all cases the thread would be the last thing to cut, burrs thrown up by which ever cutter will mean there will be some serious de-burring to do if these are put in after the thread.
 
Gray,
 
Graham
 
Thanks for your comments, they confirm my original doubts about using a ball ended cutter. The profiled woodruff type cutter is definitely the way to go but the only one I have found is in the J&L catalogue and it has a 3/4" diameter shank . Unfortunately I have no way of holding it in my milling machine as it only takes ER25 collets and the largest I can get in is 5/8"
 
One thing you have made me think about very seriously is the sequence of making the parts, I originally thought I would cut the grooves last but your comment has made me realise that would have been a nightmare.
 
Screwcutting on what will effectively be a splined bar might be interesting though. I was going to purchase a carbide thread form tool but they are not meant to be used on interrupted cuts so its now a chicken and egg situation.
 
Ian P
 
Ian P
 
22/01/2012 18:35:14
Bob
 
Maybe I did not explain it very well. The grooves are for a loose fitting pin that will act as a safety device for a 'Knock-on' type nut holding on a centrelock magnesium road wheel.
 
Although in particular case the wheels will not be taken of and on frequently, a lock washer that needed bending when it was installed is just not suitable. The thread diameter and pitch together with the physics and actual shape of the wheel forging are such that once tightened to the correct torque the nut will be self locking. The (loose fitting) pin is there as a safety measure.
 
Ian P
21/01/2012 21:06:47
Jason
 
I did suspect a ball endmill might be slow going although its the easiest for me to do with a vertical mill. The cutter in the J&L catalogue looks to be similar to what you describe (A thick slitting saw with convex radius?) but I expect that might be an expensive purchase. Also whilst I could mount it on a mandrel held in a collet its diameter might mean that the groove run out along the part would be quite long.
 
Ian P
Thread: MEW 186 - Electronic Lathe Control
21/01/2012 20:57:30
Tony
 
I liked that! (the video demo)
 
Coincidentally I am planning to make some parts in EN24T with exactly the same thread M45x2. I just know its going to be a slow job, so this ELS stuff is starting to appeal to me.
 
Ian P
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