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Member postings for Hugh Gilhespie

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

Thread: Subscription and delivery of MEW
20/02/2010 08:28:36
Lucky people! I am still waiting for Issues 158, 160 and 161. I expect that before long I will also be waiting for issue 162. This is a truly appalling service, I wish I had never bothered to subscribe.
 
 
Thread: Diamond tool holder.
18/02/2010 14:51:46
Hi Chris S,
 
I am with Les on this and am also interested in making your adapted tool holder. So, a big please and put pen to paper - or at least fingers on keys.
 
Regards,
 
Hugh
Thread: Subscription and delivery of MEW
12/02/2010 12:13:44
I also wish Peter good luck! I subscribed in late October and was informed that my first issue would be 158. It never arrived. Since then I have received one magazine only - issue 159. I called about 7 days ago to ask what was going on and was told that the outstanding magazines would be sent asap. Now I have received a letter saying that issue 158 is out of stock but my subscription will be extended. In the meantime, I stll haven't received issues 160 and 161 although they are both available as digital copies. Pretty poor service I'm afraid.
 
Regards, Hugh
Thread: Boring Question
09/02/2010 18:44:39
Hi David,
 
I am also having a problem with the RHS ads covering part of the message text. Funnily nough, it doesn't happen on Page 1 of this thread, only on the second page. I have resorted to copying and pasting into Word so I can read the posts in full. A tad irritating!
 
 
Thread: Tightening collets
03/02/2010 19:01:14
A slight variation on the collet tightening theme. I checked the runout on a piece of silver steel held in an ER32 collet on my mill today. The collet was a 7-8 mm size and I used 8mm silver steel in it so that the minimum tightening was needed. i tightened to my usual extent and was shocked that the TIR was 8 thou. The mill spindle TIR is about 0.2 thou and the collet holder was also around 0.2 thou, so it was all from the collet itself. I had to tighten much harder than I normally do to reduce the TIR to under 2 thou. OK, it's an Asian collet but even so I am surprised that it needs to be bullied so much. Lesson learned and I will take more care in future.
 
Hugh
Thread: Tachometer design
31/01/2010 13:10:52
Hi Les,
 
I am another seconder (thirder?) of wanting to keep this project alive. If we could get a few other interested tach needers, I would be happy to order all the bits needed for however many tachos and then send them out at cost to the others if you would be happy to program a few PICs? A stripboard layout would also help as my experience of making PCBs is that by the time you have bought all the chemicals etc. it end up a bit dear for a single board.
 
Anyway, over to you!
 
Regards
 
Hugh
Thread: Milling Advice Needed
29/01/2010 19:21:07
Thanks to everyone who has replied. I have now got a 12 mm carbide ripper end mill and that seems to have solved the problems. It's a bit bigger than I wanted, a 6mm would have done but I don't mind making extra chips! I am running this at about 1100 rpm with a feed of 7 inches per minute and a cut depth between 15 thou and 40 thou. I use shallower cuts near the surface as I assume these are more likely to have hard bits.
 
I have downloaded a program called G-Wizard from [email protected]
 that gives machining speeds. According to the program I could go a lot faster but I am happy enough with the cutting speed I'm acheiving and not destroying any more end mills.
 
One more question though. I am confused about whether to use coolant with carbide. I am actually using a few drops of neat cutting oil per pass and although it smokes a bit it does seem to cut down the vibrations just as effectively as spraying with suds. Over to the experts!
 
Regards
 
Hugh
26/01/2010 13:08:37
Hi All
 
As per David's excellent suggestions, I have ordered a carbide rippa from fleabay and hopefully that will solve my immediate problems. I am just surprised as I can cut this steel reasonably easily with a bandsaw so why is it so difficult to mill? Oh well, all part of the learning curve!
 
Hugh
26/01/2010 10:47:47
Hi David,
 
Thanks for a very quick response. Basically I am doing as you suggested, plunging a finished size cutter - 16 mm - at each end of the slot then using an undersize cutter to mill out between the holes. Have destroyed one 16mm cutter so far so next I will use a 16 mm HSS drill bit - at least I can resharpen the drill bit after each hole.
 
Can you explain what a fine rippa cutter is? Sorry to be so ignorant but as I said, I am very new to all this with no background in metalwork at all. I was a bit suspicious about carbide cutters not being suitable but as they cost an arm and a leg I didn't want to buy one just to see it disintegrate.
 
Thanks, Hugh
26/01/2010 09:40:41

Hi All, I am a complete beginner to metalwork and have recently acquired a Bridgeport Series 1 mill. I want to fit levelling feet to the mill and this involves using the mill to cut through slots in 150 by 90 parallel channel steel. My problem is that the surface of the steel seems to be much harder than the inside material. I don’t know what grade the steel is but it comes with a fairly thick layer of mill scale on the outside so presumably these are hot-formed sections.

 I have managed to destroy 3 HSS cutters so far. Everything is fine until I get to about 90% depth of cut. I am taking fairly modest cuts each time of about 30 thou and feeding slowly – around 5 inches per minute. I have been using 6 mm 2-flute cutters at about 2000 rpm – all OK according to what I’ve read.  As soon as I get near the bottom of the slot the cutters stop producing chips and if I try to force a cut the cutter overheats becoming red hot – end of cutter!

 I then thought that perhaps I should be using solid carbide cutter but when I phoned the technical support people at a good tool suppliers, I was advised not to use solid carbide on a manual machine and they are only suitable for CNC machines.

 I realise that there are other ways to do what I want that don’t involve milling but I would like some advice specifically on the milling and any suggestions of how to cut through slots successfully by milling.

 

Thanks, Hugh

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