Member postings for Harold Hall 1

You are correct Clive, it would be possible to slit fully across the head to make the two halves adjustable and without any loss to the working of the head. Having designed the head around 13 years ago I cannot say just why I did it that way but probably felt it looked a more engineered job if the centre portion was fully part of the main body.

With it slit fully across then a single slit to the separate the two halves would also work. I would though not like to widen the two collapsible halves and even if done I would then like the closing screws to be moved to remain central in each portion. With that said, I would still go along with the two slits as drawn to separate the two halves.

Harold

Sorry Zulu for the delay in replying but unfortunately I cannot give you a definite reason for the pages being missing. However, the most likely answer would be that my whole website was down, for some reason, at the time you attempted to view it, but you were able to view the home page as it was stored on your PC, as most browsers can do this if they are set up for storing pages viewed.

I have visited the website for the company who host my website to see if they had shut down for any reason recently. They have though produced a new website and this information does not now appear to be included.

If the site does not reappear then all I can suggest it that you contact your service provider to ask if they can explain why the site is missing.

With my website now getting between 12000 and 14000 visits a month I feel sure at least a few would contact me if the problem was widespread

Harold

Just to warn you, Ray, there is a small error on the drawings, not too serious though, you do not end up with scraped parts. Rather than detail it here it is included on my website, see this page.

In use, typically, it can produce some useful divisions, such as 125 for a 8TPI leadscrew dial, and 96 used in clock making, neither of which can be achieved with the Semi Universal Dividing Head. In both cases, as in almost all others, it could not be simpler as one has only to step from gear space to gear space so it is impossible to make a mistake. If you do move through two gear spaces then it becomes obvious and it is just a case of moving back to cut the missing gear, or engrave the missing line.

For the lower number is does of coure require one to move through more than one gear space. Just mark the gear with a marker pen before placing it onto the dividing head

Even producing 360 divisions one just has to move one gear space at a time. But in this case there is a surprising result. As you move from gear space to gear space it will be seen that some divisions are missing. However, when you complete one turn of the gear being used, then going round again it will be seen that some of the missing division then start to be made. It is a case of keep going until all the divisions are completed. It is still impossible to place a division in the wrong place. One minor complication of this is that it is difficult to know where the longer lines have to be. But making them all the same length first, then going round again to lengthen those that need this is not particularly difficult.

Harold

Edited By Harold Hall 1 on 21/04/2015 11:14:15

Certainly not an idea solution, Dave, but for very occasional use you may get by with this idea, and it doesn't take long to make.
Harold

Something that I feel is very often overlooked is that for an endmill it is only the extreme tips of the end cutting edges that are required to cut metal. For a four tooth endmill this will be one quarter of the feed rate per revolution, I would think, no more than 0.05mm even for a roughing cut in the home workshop.

The requirements are for the four tips to be at the same level and the edges to be ground so that the overall result is concave. I have on my website a very simple device for achieving this.

Slot drills are of course different as they required to plunge like a drill, but the device above will still sharpen these also. However, as one edge is longer than the other it needs a little different approach. Both edges are first sharpened as for an end mill but then the device is set so as to create a slightly greater concave result when only the inner section of the longer edge is ground. This makes the edge slightly bent but maintains both tips at the same level.

It will only take about 3 hours to make and this can be reduced if the alternative mounting method is adopted.

Harold

It occurs to me that a few facts, stated simply, may help those coming to terms with the common jig

1. No setting is critical but getting the rotation close to 180 degrees between edges is very desirable.

2. A lower drill projection from the jig results in greater backing off angle.

3. Greater backing off results in a greater chisel angle.

4. Greater chisel angle results in a longer chisel

5. A longer chisel results in more metal being removed by the chisel and less by the cutting edges.

6. More metal being removed by the chisel results in a greater force needed to drill the hole.

7. Conversely, item 2 typically. A greater projection from the jig results in a lower backing off angle.

8. Larger drills will need a larger projection.

9. The drill should be set in the jig with the cutting edge to be ground vertical.

10. After completing edge one the drill should be rotated 180 degrees as close as is possible. See note below.

The aim therefore is to get the chisel angle close to 130 degrees, though this is not critical. A small metal plate, scribed at 130 degrees to the edge, and held against the drills cutting edge will be more than adequate, perhaps also scribed at 120 and 140 degrees to set the limits.

Having adequately sharpened one drill, preferably a largish one, record the value that the drill was projecting from the jig. With a few drills sharpened and recorded, estimating the projection from the jig for intermediate sizes should be more than adequate.

I would suggest viewers visit my website pages on the subject of sharpening drills and where a simple device for accurately achieving the 180 degree rotation is illustrated.

Harold

Julie

I have the six remaining issues available, also 4490 should you like them from one address

PM me with details of the address to send them to.

Harold

I am Clive a little surprised regarding your comments on my published ideas on the subject of sharpening drills using the very common jig. My surprise is based on the fact that I get perfectly acceptable result using my approach. However, I am not the only one, a few on this forum have commented that a jig, stored away for some years, has been brought out and tested using my suggestions and with very good results, others have e-mailed me with similar comments. On the basis that not every one adds such a comment to the forum, or send e-mails there must be quite a number of other users satisfied with my approach.

I am though prepared to accept that I am not foolproof so would be very happy to receive your comments as to where I am wrong, If you make a quick flit through my web pages on the subject and reply here this will both help me and those on the forum who visit the pages. Thanks!

Please though take note that I am not concerned with the finer details of the drills geometry only that it produces drills that cut well and to size. For me, if the drill angle is say 116 degrees or 122 degrees I am not concerned. similarly the chisel angle if its a few degrees off 130.

Harold

Why no advice for Kevin from those who carry out their milling tasks using the lathe, in particular using a vertical slide. Do give him the benefit of your experiences.

Harold

When milling on the lathe it has to be accepted that this will limit the size of projects that can be undertaken. That having been said some interesting ones can still be undertaken.

Because of the limits mentioned above, the choice of slide should be to maximise the size of work that can be undertaken. The first place to look is obviously the Warco website. On there there is a nice looking slide but in checking the spec it is only 50mm wide, very limiting! This can be seen on the page here, where the method of mounting (bottom of the page) it horrifies me, please do not use the method.

Warco also offer a Myford style of vertical slide which is 100mm wide giving much more scope as to how it can be used. This, therefore, is the one I would recommend. If cash will stretch to it then you could consider the swivling version but for most users this added facility serves no purpose, only you can chose depending on the tasks you anticipate will occur.

For a vice, I cannot recommend other than a toolmakers style of vice. The advantage is that the vice can easily be positioned on the slide in such a way as to leave the traverse fully available for the machining to take place. See photos 4 and 5 on these pages. These illustrate that the toolmakers vice (Photo 4) can be slid up and down to get the work into the best place leaving the slide's traverse fully available. The vice in Photo 5 cannot achieve this.

See the follow pages for an introduction to milling on the lathe which may be of help.

I commented earlier how the size of projects will be limited, however, see the pages under the heading "lathe only Projects" which illustrate that very interesting projects can be undertaken.

Harold

As has been rightly said, David, you will need some clamps for securing items to the work table, but as you say cash is going to be tight in the early stages I would suggest making your own. This will leave more money for items you cannot make.

See here for some ideas, particularly photographs 3 and 8. The lighter weight clamps are also more adaptable for using on an angle plate or the lathes faceplate. You can, in the first case, make a couple of temporary tee nuts using a hack saw so as to secure your vice for making more.

Harold

Sorry Thor for the delay in replying.

I have to admit that having changed most of the pages, one at a time, I was finding it a little tedious by the time I got to the index and left the index entries as they were. The reason being that each entry is grouped with the link to its left so that it is easy to open up the list at any point to add new entries as the index develops, making it, for each one, ungroup, change font, regroup and onto the next one.

Hoping this will be "at least for now", as you say.

Harold

I have used the method suggested by Maurice (Mo) with satisfactory results, actually providing an article in issue 8 of MEW regarding the method. It's first use was to produce a plate having 125 holes. However, I did not have a computer and asked the draughtsman in my department to produce a printout. It was printed using pen plotter onto film and was very accurate.

Subsequently, when I had acquired a PC with a CAD program I printed out my own using dot matrix, inkjet and laser printers. With these, I have always found that the large circle on which the divisions are placed is very slightly oval, typically an error of 0.5mm on a 100mm circle. Whilst this would have minimal effect on the accuracy of the divisions, the detent on my dividing heads could not cope with this. Rather than go into detail here, my solution to this can be seen in Photo 16 and associated text.

I have also used the method of producing the plate on the milling machine using the coordinates for each hole to position them, as implied by the use of CNC and DRO's mentioned by some above. Unfortunately, most will not have these facilities available and for them my pages on placing holes on a PCD may be helpful.

These basically use the method implied by John S when he started one of his comments by saying

Rough and ready Excel spreadsheet."

Thanks Ian, I had not thought of that, will give it a try should I want to produce any more files for my machine.

Harold

If you are still viewing this thread Johnboy then can I suggest you give my website a visit to look at a few of the pages now that I have changed the font used, at lease for the vast majority of pages, explanation later.

I have changed from Times New Roman 16pt to Tahoma 14pt which resulted in the text taking up very slightly less space. Because of this changes to a pages layout were few and far between so that the time taken was not that great. Also, suffering with a cold, with complications, I was house bound for three weeks so allocated most of this time to the process and have completed it much quicker that I had thought I would.

The reason I say above, "vast majority" is that a few items have lists, or formula, which benefit from being displayed with a mono spaced text. These have therefore been left using Courier New, which is a simpler type face in any case.

For me the original fount was not a problem to me viewing the pages on the web. However, when I am working on the pages I like, if possible, to view the page as a whole. In this case I do find Tahoma beneficial so I have gained something out of the process.

Harold

If anyone is not happy with files cutting on the upstroke then the method I adopted for modifying standard files, for use on my filing machine, could easily be used for modifying needle files.

Details are here on my website, modified files

Harold

I think I should opt out I see I have made a mistake I should have said

That is why myself and others on this thread were taught, a very long time ago, that foot- pounds is used only for power and pounds-feet for force which eliminates the ambiguity. I am though surprised to learn that that approach has been shelved. Too late to challenge the tutors though it was 66 years ago.

Harold

I agree Capstan I did not fully take in the per time aspect of what you are saying. But now see we are basically in agreement. Foot pounds, on its own, is a quantity of force, but foot pounds needs quantifying by "per minute"if to be used for power. As you say the terms used like that are ridiculously vague.

That is why myself and others on this thread were taught, a very long time ago, that pounds-feet were used for power which eliminates the ambiguity. I am though surprised to learn that that approach has been shelved.

I think we can now agree to agree.

Harold

I have now looked at Wikipedia which states

The foot-pound force (symbol: ft·lb_f or ft·lbf), or simply foot-pound (symbol: ft·lb) is a unit of work or energy

Also says Not to be confused with Pound-foot (torque) or Foot-poundal.

Then on another page

A pound-foot (lb·ft or lb_f·ft) is a unit of torque

I have to admit that it goes on to say

However, the torque unit is often still referred to as the foot-pound

To me that is a very risky thing to do and easily open to errors. Would be like using the term voltage for both pressure and power

Harold

I am sorry Capstan but I was happy to be told I had got them the wrong way round but cannot accept that both torque and power have the same term for the unit of measure.

If I were to tell you that the result of experiment was 15 pound-feet can you tell me what that answer means?

Surely torque and power need differing units of measure, that is the way I was always taught, still it was a very long time ago.

Harold

Edited By Harold Hall 1 on 02/03/2015 15:31:08