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Member postings for Jim Greethead

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

Thread: Help with poor finish when cutting with the side of the cutter
01/01/2012 10:06:54
Thank you all for your good advice to Nic which I have also taken on board.
 
There are many things to try and I have found that a climb milling cut on the same setting improves the finish as does the use of WD40.
 
I have ordered a copy of Tubal Cain's book and will examine it with pleasure when it arrives.
 
Ultimately, I suspect that Chris Gunn's advice will prevail but I will have learned something on the way. And that is part of the pleasure.
 
Happy New Year to all of you.
 
Jim
 
Thread: Yet Another Tangential Tool Holder
30/12/2011 19:58:05
Sudden thought: would it be possible to braze a carbide tip onto a piece of 1/4" x 1/4" mild steel to use with a tangential tool holder?
 
Maybe a discarded indexable tip ground on a green wheel.
 
Might have a go when the dizzy season slows a bit.
 
Jim
 
Thread: Help with poor finish when cutting with the side of the cutter
30/12/2011 19:49:19
Good question Nick, I have the same problem but I didn't think to ask. I will be watching with interest to see if there is anything I can do to improve the finish. It could save a lot of filing and polishing.
 
Thanks for the interest Jason, I have a feeling that you might be able to help here as you have in other threads.
 
Jim
 
Thread: Morse Taper Removal
25/12/2011 08:58:49
That sounds about right Terry, it is really just a drop of an inch or two under gravity with the lump hammer. I could use a lead or copper hammer but I don't have one and probably don't need one for this job.
 
Everything clean and definitely no lubrication.
 
'Ave a good one.
 
Jim
 
Thread: Merry Christmas 2011 from the staff of Model Engineer
25/12/2011 00:29:01
Merry Xmas to you and all the staff David and remember:
 
El Ilegitima nil grindem carborundum
 
Jim
 
Thread: Christmas 2011
24/12/2011 21:34:36
I found this on the HMEM website. It tickled my fancy:
 
Please accept with no obligation, implied or implicit, my best wishes for an environmentally conscious, socially responsible, low stress, non-addictive, gender neutral, celebration of the winter/summer solstice holiday, practiced within the most enjoyable traditions of the religious persuasion of your choice, or secular practices of your choice, with respect for the religious/secular persuasions and/or traditions of others, or their choice not to practice religious or secular traditions at all; and a fiscally successful, personally fulfilling, and medically uncomplicated recognition of the onset of the generally accepted calendar year 2012, but not without due respect for the calendars of choice of other cultures (the Mayan's won't be here next year), and without regard to the race, creed, color, age, physical ability, religious faith, choice of computer platform, or sexual preference of the wishees.

By accepting this greeting, you are accepting these terms. This greeting is subject to clarification or withdrawal. It is freely transferable with no alteration to the original greeting. It implies no promise by the wisher to actually implement any of the wishes for her/himself or others, and is void where prohibited by law, and is revocable at the sole discretion of the wisher. This wish is warranted to perform as expected within the usual application of good tidings for a period of one year, or until the issuance of a subsequent holiday greeting, whichever comes first, and warranty is limited to replacement of this wish or issuance of a new wish at the sole discretion of the wisher.

Regards,
 
Jim
Thread: Morse Taper Removal
24/12/2011 21:31:39
Sounds a bit long-winded Michael: use spanner to loosen the drawbar a bit, pull down (or fit) the lever, move lever out of the way, unscrew drawbar.
 
Certainly, it eliminates the "whack" but after the foregoing posts, I wonder if that is a problem.
 
Now if you attached an air hammer to the lever ...
 
It is Xmas - must go and check if Santa has left any goodies in the workshop.
 
'Ave a good one, all of you
 
Jim
22/12/2011 10:43:12
Ian: The spanner I needed was 13/16" ( and you reckon metric is weird) and I was after a tube spanner because I have a cunning plan. I would still like to have the spanner and hammer on the drawbar but to avoid the problems associated with the moment of inertia. So ... I am thinking of putting a spring under the spanner so it is not locked to the drawbar and then incorporating a heavy handwheel that can tap out the tool.
 
And if that does not work, I will cut the tube spanner in half and put the hammer on the other end and a handle in the middle.
 
And if none of that works, keeping it in a loop in the vicinity sounds good.
 
And yes, I am aware of the limitations of the Jacobs chuck and would never (well hardly ever) apply radial loads to it. But for counterbores, it is just acting in the drilling mode so I thought it would be alright. I must admit that I had not considered your scheme of setting up the various tools in their collets but it makes sense and is probably no more time-consuming than using the Jacobs chuck. Thanks for the tip. And for the other suggestions.
 
Jon: I must check the cutter. It is relatively new and has not done any serious work. It is not a Dormer but I think it came from a reputable source.
 
Thanks for the continued discussion
 
Jim
 
22/12/2011 07:18:14
Ian (Berto) would you believe it? Today I went in search of a tube spanner to convert into a "spanner/hammer" but the cupboard was bare. Spanners smaller and larger were available but the rack holding the ones I need was empty. So maybe lots of others have been reading this forum and have beaten me to it. Or maybe not.
 
Thanks for the additional explanation Jon. It sounds like I am stuck with the limitations of the HM45 added to my own limitations. Just as well bog and paint are still available.
 
And then yesterday, I tried to counterbore a 1/8 inch hole using a 1/4 inch 3 flute end mill in the Jacobs chuck (yes, yes yes, but I had several holes to drill and counterbore). I am not sure if what I saw was "orbital precession" but the cutter seemed to be walking around the circumference of the hole. The counterbore measured 7mm.
 
I have yet to try the other combinations: using drill for counterbore (the bottom need not really be flat), use collet chuck for the 3 flute cutter and use 4 flute cutter in the Jacobs chuck.
 
I have certainly used milling cutters in the Jacobs chuck for counterboring before but usually, I am watching the depth of cut rather than the actual operation. But I am usually cutting aluminium (this was cast iron) and don't usually get oversize holes.
 
I just thought it was a bit of a coincidence after the discussion.
 
Jim
 
20/12/2011 19:57:25
Thanks for the explanation of "quill bounce" Michael, I have not previously heard it called that (or anything really) but I always lock every axis that I am not cutting along. Interested to learn that locking the quill does not cure the problem.
 
I guess these small things add up to make the difference between the surface finish I get on the HM45 and the one I got on the HAAS CNC machine in the course I did at Tech this year.
 
Now "orbital precession": could it be the axis of rotation of the quill wobbling like the axis of rotation of a spinning top? And if so, what order of magnitude of error does this cause?
 
Thanks for the continued interest and for exercising both remaining neurones.
 
Jim
 
20/12/2011 06:42:00
Jon: I am pleased to know that I am not the only one with small piles of all the necessary bits for things just waiting for me to decide that they are the next project. They usually wait until the current project has disheartened me or everything else looks too hard. Sometimes the piles get raided for things needed elsewhere of course.
 
Michael: What is "quill bounce"? When I googled it, I got a video of several children jumping on a trampoline plus a number of other suggestions that didn't look too much like a milling machine problem.
 
I am now back home after the usual Ho Ho Ho run to see family in Sydney so I can give some thought to Ian's "spanner/hammer".
 
Thanks to all for the continued interest
 
Jim
 
Thread: Rina and T&K drawings
20/12/2011 06:24:02
Hi Norman,
 
In regard to the dimensioning, John Olsen has redrawn the whole engine in Alibre and I can send the files to you if you wish. Alibre is a 3D CAD program that John convinced me is the simplest and cheapest way to produce 2D drawings. You can download the full program on trial for 30 days for free and the Personal Edition (that I use) is $199. It took me about 1 week to become reasonable proficient in using it and less to do simple things like producing dimensioned 2D drawing from the 3D parts. I can recommend it.
 
I have redrawn the engine (using Alibre) converting the imperial measurements to rational metric including metric threads. I have also modified it a bit to suit my limited capabilities and natural disinclination to file complex shapes when I can cut stuff with a slitting saw.
 
In producing my version I have, in parts, been too clever by half with the result that I have had to backtrack and revise my design several times. But that is life I guess.
 
Send me an email to greethead@hotmail.com if you would like the files. If you would like to talk, my Skype address is jimgreethead.
 
Jim
 

Edited By Jim Greethead on 20/12/2011 06:30:21

Thread: Morse Taper Removal
18/12/2011 21:13:07
Hi Ian,
 
Your "spanner/hammer" might be the go, at least until I get sufficiently enthusiastic and build one based on an air hammer.
 
Pity about the little handwheel though. One side effect was that running the drawbar up and down was done with a flick of the handwheel instead of that tedious thumb & forefinger work (lazy? Too right I am). There wasn't much flywheel but it seems that the bit that worked here was the bit that loosened the drawbar.
 
I am still puzzled about the drawbar coming loose. As someone pointed out, the cutter load will tend to tighten the drawbar. The only thing I can think of is that I was using a profiling cutter which makes heavier interrupted cuts than an end mill. I think that the start of each cut slowed the motor just a bit (and tightened the drawbar) but then the motor accelerates again which tends to loosen the drawbar. I think the loosening effect is greater than the tightening effect.
 
Michael: Thanks for the photo. I think the air hammer one is the one I was thinking about.
 
And I am still thinking.
 
Merry Xmas to all of you and thanks again for the stimulating discussion.
 
Jim
 
Thread: Rina and T&K drawings
18/12/2011 20:55:26
Norman,
This is how Metalbutcher cut it out of a solid block of aluminium and I intend to copy his example.
 
 
Because I am using a flywheel without spokes, I increased the size of the disk on the governor bracket to 38mm diameter to make it a bit more solid.
 
This thread on HMEM has provided me with lots of good ideas and some much-needed inspiration to consider dud bits as "practice" and keep going.
 
It is nice to know that someone else is building Rina, I thought I might be the only one. Good luck and how about some photos of progress to date.
 
Jim
 
Thread: Morse Taper Removal
17/12/2011 22:28:11
 
The plot thickens
 
Jim
17/12/2011 22:03:02
You blokes are proposing some really ingenious ideas and I am enjoying the discussion. Maybe the topic has arisen before John, but it is not easy to find it on the Forum.
 
Ian: I am not sure I understand what you are saying here because the handwheel is locked to the drawbar with locknuts on each side. I will, however, check that it is not bottoming in the collet chuck. Thanks for the suggestion.
 
Nigel: I keep thinking about that extraction tool. With a collar on the spindle, the world is the molusc of your choice; it opens a range of possibilities. If the extraction tool was modified so it could turn the drawbar, you could do away with the extraction bolt, unscrew the spindle until the extraction tool contacted the bottom of the collar and keep turning to press the drawbar out. It would require a lever on the extraction tool but then the tool could be used to tighten the drawbar as well.
 
Does anyone know how those automatic drawbar insertion and release mechanisms work? They sound like those air hammers used to tighten wheel nuts.
 
Jim
 
16/12/2011 21:31:04
Thanks Nick, that explains it
Jim
 
16/12/2011 20:05:31
Peter, of course you are right. I have just checked the drawings for my mill (why didn't I do that before making an idiot of myself) and the bearings do, indeed, take the shock load. Pardon me while I take my foot out of my mouth and bash my head against the wall
 
Gordon: That sounds sensible. They don't provide any alternative so perhaps they have allowed for it.
 
Steve: I did a course at the local Tech recently and this was still the method of removing chucks. One thing I did notice was that, as you say, it was usually a lead or copper mallet rather then the steel lump hammer I have been using. Are the soft hammers more gentle on the machine?
 
Dusty: Good advice. And following Gordon's admonition to use one big whack rather than a lot of little ones, I guess the correct size hammer is the biggest one at hand.
 
And lastly, thank you all for your contributions and for keeping me on the straight and narrow. I appreciate it all.
 
Jim
 
16/12/2011 10:58:39
Sorry, I should have said that the collet chuck came loose. It came out of the spindle because the drawbar had unscrewed.
 
It was a bit odd because it came out, the cutter gouged the job and then it bounced back and tightened up on the drawbar. So when I stopped the machine and checked, the drawbar was tight.
 
Thinking there was something mysterious going on, I started work again. When it happened the second time, I twigged. And tightened the drawbar with a spanner. That fixed it.
 
It is possible that the inertia of the handwheel causes it to loosen when the spindle accelerates. That happened when I used a steel handwheel. So I swapped it for an aluminium one having less inertia. It seemed to be ok but maybe several starts caused it to loosen.
 
Next step is to try a handwheel with less inertia but more hand holds - like the tap handle shape.
 
I am reluctant to give up altogether because it is just so much more convenient than the spanner and hammer method.
 
Jim
 
16/12/2011 06:55:59
I had a lovely time today swapping from Jacobs Chuck to Collet and back again using my new lashup and thinking "what a clever boy I am".
 
Right up until the collet came loose and the cutter gouged a piece out of the job I was working on.
 
Luckily, Murphy was Xmas shopping so it was not the last cut of a complex piece, and it didn't ruin the job.
 
So tools in the taper need to be more than hand tightened. Or it needs stronger hands than mine. Or I need to redesign the handwheel ... maybe something like those bathroom taps with the cross on the top to give a better purchase.
 
What do you reckon?
 
Jim
 
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