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Member postings for Tony Pratt 1

Here is a list of all the postings Tony Pratt 1 has made in our forums. Click on a thread name to jump to the thread.

<< First < Prev 111 112 113 114 115 116
Thread: Tap Magic
19/01/2010 19:24:39
Hi Gordon, do you mean "Tapmatic" cutting fluid by any chance? It was a slightly yellowish thin liquid.
 
Tony
Thread: Lathe, lowest speed?
06/01/2010 21:23:36
Hi, from my experience 50 rpm will be fine. Obviously there will always be that job which needs a slower speed but not too often.
 
Tony
Thread: Milling cutters with screwed shanks
06/01/2010 21:19:58
Hi, from a quick Google search the thread profile is Whitworth and all are 20 tpi, irrespective of O/D.
 
Tony
Thread: HTS Bolts
01/01/2010 19:54:58
Ok, I'm going where angels fear to tread.There is no absolute right number of clamps, 3 could be ok or you might need any number, some long jobs or irregular shapes require large quantities of clamps to prevent movement.
The only time a job will not be distorted by clamping is when the underside is fully supported either by its lying flat on the table or if so required shims or jacks are used to take up any irregularities, therefore when clamping commences the clamps are acting on a fully supported surface. If these precautions are not observed there is always a risk of distortion irrespective of how many clamps are used.
 
Tony
 
01/01/2010 13:21:45
Hi Frank, I don't believe any one said that MS bolts "stretch too much". From my old college days I think I am right in saying that any bolt will stretch when put under load, MS more than HTS for the same load, they will return to their original length once the load is removed unless they have been taken past their elastic limit. I await the definitive answer on this one as it's been a fair few years[too many] since I was an apprentice.
Tony
01/01/2010 10:42:50
Hi Ian, nothing wrong at all with using HTS bolts, as you say mild steel does tend to stretch a tad ! I know exactly what you mean about clamping correctly, it's easy to do the wrong thing if not shown the correct way. I have also seen plenty of so called skilled men create some appalling lash ups, but that's another story.
 
Tony
31/12/2009 19:14:48
Hi John, pushing a bolt through the tee nut is indeed unwise, if the stud is damaged on the threaded portion which your clamping nut is on [a lot are], when you tighten up,the stud will try to jack the tee nut higher in the slot rather than clamping the job.
In many years of commercial machining I can't recall ever using high tensile studs or bolts. If you are applying enough force on one clamping location to need high tensile studs etc. you will be seriously compromising the tee slot itself. I have always found the more clamps you can apply the better.
 
Happy new  year to you all,
 
Tony
Thread: Thread cutting on the lathe
06/12/2009 16:10:45
Hi Lawrie, as Anthony says what thread are you cutting ? As a general rule the thread depth is the difference between the crest dia [outside dia] & root dia[minor dia] divided by two but that tends to be a theoretical figure. In my experience the bore is machined oversize on minor dia. to make sure there is no fouling on the male screw O/D and the internal thread is cut to fit the male part [or gauge].
Are you using a single point tool screw cutting tool & have you a male part to fit the internal thread to?
Tony
Thread: Glanze Parting Blade - question
28/11/2009 16:43:48
Hi Anthony, I have just had a rummage in my "Tooling" store and have actually got a Glanze parting blade and tip which I can't even remember buying and certainly haven't got round to using, unfortuanately no removal tool to be seen !!
As Paul suggested I had a go at tip removal with an allen key. A 1/8" A/F fits a treat and a slight turn free's the insert, worth a go if you are stuck.
I believe Meyrick is right in what he said about Sandvik tip extractors, I do recollect some plastic handled thingy now he has jogged my memory.
 
Tony
27/11/2009 21:14:36
Hi Anthony, I haven't used this particular brand of parting blade system but I would imagine it is the same as the Sandvik / Kennametal / Iscar parting systems I have used in an industrial environment. There is indeed a special tool for removing the inserts, it is basically a piece of bent 5mm dia? rod [proportions as per an allen key] The small end is flattened to about 1/3 its dia.
The tool is placed behind the insert to be removed and a quick twist will free it. When I put a new insert in place I like to give it a light tap with a piece of Nylon to seat it. All the parting tools I have used came with this tool as standard so give Chronos a ring and I am sure they will send you one.
 
Tony
Thread: Taper cutting
14/11/2009 13:25:57
Hi Ian, yes that's true about the centre holes etc, but he does seem concerned about work hardening on the O/D etc.
 
Tony
Thread: Hints and tips
13/11/2009 21:22:46
Hi Chris, spiral taps, oh, happy memories! In a previous life I used spiral flute taps [always M6] to tap literally 1000's of holes in HSS tool blanks whilst my Wire Eroder was cutting on generally long cycle times. I had forgotten about them but as you say they are great to use and the swarf comes out in strings.
I will go and have a look in my toolbox to see if I still have a couple of these good old tools left which I can bring out of "retirement"
 
Tony
13/11/2009 20:44:07
Tapping tip, although taps come in sets of three, taper, second & plug you rarely need to use all of them. Just use the taper tap, remove the swarf produced by any means at your disposal and then finish the hole with the plug tap again cleaning the hole to finish.
Also always countersink the hole before tapping, or drill a couple of threads deep with a clearance drill [which is my prefered method] so the threads start below the work surface.
 
Tony
Thread: Taper cutting
13/11/2009 20:03:27
Hi Hilton, it is certainly strange that neither HSS or carbide will cut this material if they are sharp and on centre line, carbide will certainly cut hardened steel to some degree depending on the grade you are using.
Another check you can do is to get a decent file and try to mark the corner of your workpiece when it is nor revolving, this rough and ready method should at least tell you if the steel is soft or not. Let us know how you get on.
 
Tony
10/11/2009 21:18:54
Hello Hilton, when you say you are getting hardly any cut do you mean the tool or top slide  is pushing away or the tool is wearing as it tries to cut the job? Also what is the cutting tool mtl?
 
Regards,
Tony
Thread: "Precision" or "does NOT do what it says on the tin"
04/11/2009 18:25:43
Hi Chris, my sympathies and understanding. I have worked in Toolmaking all my life and when we used  quality european or american tooling it would be made to a recognised standard and the accuracy of collets etc when new would be very good indeed and if not they would have to answer the question "why not"? You of course paid a very high price for this guaranteed accuracy.
I am now  not in Toolmaking and just run a hobby shop and like all of us have been seduced by nicely ground shiny things at ridiculously low prices [this is one of the reasons we don't have any manufacturing left in the UK], but I wouldn't be suprised at all if the accuracy was not too good.
It is very worrying that you are getting a wobble on your test bar and I don't think it is just the difference in diameters which is the problem as I would have thought the front taper would tend to selp centralise and align your test bar but I may be wrong. To me it seems as if the chuck bore is not truly square to the rear reference face.
It will be very interesting to see what specs the chuck is made to, if any. Please keep us informed on how you get on.
 
Tony
Thread: Grinding hss
21/10/2009 19:29:29
I too dip all my HSS tools in water when I am sharpening them as they can just get too hot to handle. In my nearly 40 years as a Toolmaker I had no problem with this practice and no one ever said it was detrimental [ although in theory I am sure it is !] I never dipped carbide in water after grinding.
My latest practice at home is to rough with a tipped tool and finish with a nicely honed HSS tool, I believe I have arrived at the best solution for me.
 
Tony
Thread: Screw Cutting Dog Clutch
19/10/2009 21:38:39
Thanks Michael, that site has given me some much needed guidance.
Tony
16/10/2009 12:47:48
I am just re-reading the excellent "Screw Cutting In The Lathe" by Martin Cleeve and fancy making a dog clutch for fast and repeatable screw cutting. Has anyone made a similar mechanism as described in the book as I would like some pointers if possible ?
 
Tony Pratt
<< First < Prev 111 112 113 114 115 116
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