Member postings for Harold Hall 1

Ady You may find the article on my website of help as it deals with the three methods that can crop up in the home workshop.

1. A conventional gear driven by a conventional worm where the two axis are at right angles to each other. Due to the engagement of the two gears not being ideal it is unlikely to appear in commercial equipment.

2.Generally as 1 but with the worm gear set at an angle to the worm wheel axis to improve the engagement of the two gears.

3. The worm wheel having its teeth cut at an angle so that satisfactory engagement can be achieved with the two gears axis at right angles to each other. Even better, the worm wheel can be cut in a concave form so that the wheel wraps partially around the worm gear.

Method 3 is not of course applicable to your situation as the worm wheel already exists.

The web pages also deal with calculating and setting up the required change wheels, See the following Web page

Harold

Thanks David for the information.

Now with David's figure of 8 drawings of individual parts per page and with there being 1600 machined components that equates to 200 pages. With there being a few less pages of text (compared to my original estimate) and a few more pages of photographs the total becomes 253 pages. At four pages per issue that becomes 63 issues nearly five years of MEW.

If, John, you want to get your efforts into the public domain then creating your own website for it would seem to be the way forward and can be very rewarding personally. There would of course be some cost in having the website hosted, probably around £50 per year.

Some have suggested this forum could host the project but it would be very time consuming for the owners to add the pages to the site for which they would get little reward. And then, who would be responsible for receiving the inevitable questions that an article of this magnitude would produce.

Harold

Personally, I am too busy to give each magazine more than a quick glance, so I am not really in a position to comment, However, I have been prompted to estimate from John's details of the article just how many pages would be required. Of course, not seeing the drawings makes estimating the pages for these somewhat hit and miss. Even so, drawings in the magazine are printed larger these days which is good making them easier to read, especially with the amount of white space often used.

So at

1600 words per page-------------------- 31 pages

Two A4 drawings per page ------------110pages

10 Photos per page------------------------23pages

Total 164 pages making, at 4 pages per issue, 41 issues, just over 3 years for MEW and I have made no allowance for the large headings used. This is nearly twice the size of the Stepperhead construction series.

It has been suggested that some of the date could be added to this forum, may work but can it be guaranteed that the data will still be available for someone reading the article in say 20 years time, I am not sure.

Harold

The situation with the Myford John WI is that when fitted with a gear box the quadrant is used primarily to switch from thread cutting to fine feed. A clip is swung out of the way, a pair of gears removed and replaced the other way round and the clip replaced, this is very quick and easy as the gears are linked together. The setup is then in fine feed mode. However, unfortunately, the quadrant does not lend itself to fitting a conventional gear train and an alternative quadrant has to be obtained. Also gears for the purpose are not therefore supplied with a lathe fitted with a gear box. I do not know if any other lathe makes have this limitation.

In my case, I purchased a gear box, with the necessary quadrant, etc, to fit to the lathe, as a result I still had all the gears in the standard set together with the quadrant for non gearbox lathe. The quadrant did not fit the lathe, now fitted with a gearbox, and wanting to set up for a worm gear, it was a case of make or purchase a quadrant to suit the gear box, I actually decided to make one.

The program on Lathes co uk sounds interesting, I must find time to look at it.

Harold

If you go with John's idea of setting the gearbox to 8TPI then you may find the lists on my website of interest. I have calculated (well the computer has) every combination possible using 14 gears and an 8TPI leadscrew. This results in over 66000 combinations, extracting only those between 6TPI and 50TPI still leaves over 37000.

If you go to my page here and click on "12+ to 14" and scroll down to 12.5 you will find there are 17 combinations that achieve this number. Thirteen of which use 3 drivers and 3 driven but four combinations only 2 drivers and 2 driven which are obviously the ones to consider first.

The reason for quoting all is that the user can then chose a combination that can be set up using the available gears. One, two or three missing gears will rarely be a problem therefore. Unfortunately, most lists only list a single set up for a given TPI, this can easily give the beginner the idea that there is only one setup suitable and buying a missing gear to make the TPI required possible.

Having a gear box on the lathe unfortunately means that the fitted quadrant is unsuitable for setting up special combinations and a quadrant specifically for the purpose has to be purchased or made. If the later then this page on my web site may be worth looking at.

Incidentally, the list of combinations is particularly useful when worm gears are being machined as these almost always have very complex pitch value.

Harold

I very largely agree with you Bandersnatch, in retrospect I should have said a little more information. In this case, just the details of machine would be sufficient for starters. Having this then the answer would be rather different if we considering a mini mill compared to a Bridgeport. Of course, if the later, it is likely that the owner would be sufficiently knowledgeable not to need to ask the question, but we do very occasionaly see a beginner being able to afford and house larger machinery.

My apologies Murray if I misunderstood your reply, but as you started by saying “Sounds like pussy footing about to me” I though you were referring to using the two stage method for producing dovetails. However, it is obvious that you are using relatively robust machinery and maybe you , as with many others, may not be aware the situations that those with lighter duty machines often have to contend with.

For an example, I quite often receive emails from those who have made one of my designs and stating that they have made it predominantly with aluminium as their milling machine is only a light duty one. I have even known the grinding rest, which started the thread, being made mainly out of aluminium. In this case, the maker in his email referred to the accessories not moving that easily over the table top, and could I suggest anything to overcome this.

I cannot remember the actual answer I gave, probably to attempt to make the table out of steel. I do though remember I suggested he could try “Slick Tape”, low friction tape used, typically, by woodworkers in their router jigs. As I had some of this for my cabinet making activities I intended to try out the suggestion on my own rest. Unfortunately, around 10 years later, I have not found the time to test it out. I must try to find the time, what a hope.

For anyone reading this who would like some more detail about the tape then it is sold by Axminster, and no doubt others.

Harold

Thanks Mike for the info I think perhaps you will need to use the two step method.

Incidentally, when I mentioned more info from the OP I was not aiming at yourself specifically, I often think the question being asked should be back up with a more detail.

Also, as you are making the item from the 25 year special you may find some additional detail that I have included on my web site worth considering. There is also an expanded drawing of the upper section that enables the fine detail to be more easier understood. Links to the various comments can be found on the rests main page here

Harold

I am sorry Jon and Murray but you are trying to advise Mike without knowing the machine he is using, I doubt if one in a hundred workshop owners have power feed, loads of coolant and an airline to dispose of swarf.Also, my experience, through my web site, is that less than one in four have a really robust milling machine.

You are of course not the only ones to fall into this trap, it so often happens on this web site. On the other hand, the OP could provide more information as to the machines, etc. being used.

Also Murray, cutting a tee slot is quite different to cutting a dovetail as material is being removed on both side so there is very little attempt to force the cutter sideways. Of course, one side is climb milling whilst the other is conventional milling so it is not perfectly balanced.

My advice Mike is, if you have a largish cutter and a robust machine, then attempt it in one pass, but if you run into problems then revert to the two stage method as you so clearly illustrate in your drawings. These, prove the saying, a picture is worth a thousand words.

Harold

If I may be allowed to give a plug for my book "Metalworkers Data Book" it gives thread forms, pitches, core diameters, tapping drill sizes, % depth of thread using the quoted drill sizes, dimensions given in both metric and Imperial, etc. and for the following thread types

Metric course
Metric fine
Metric Spark plugs
Metric conduit
BA
UNC
UNF
BSW
BSF
ME
British standard brass
British standard cycle
British standard pipe parallel
British standard pipe taper
National pipe taper
Metric threads recommended for model engineering
The book gives outline drawings for their thread forms .

The book also has details for many other subjects,see link above for details

Myhobbystore have it listed here

Harold

Alan

You only mention a lathe so I assume you do not have a milling machine. In this case my website details in depth how to make a small Stuart 10V/H using just a small lathe and small drilling machine. Even if you have a milling machine I think the webpages are still worth a visit. The web pages can be found here

Harold

You may find, Tom, my method for producing a barrel shaped con rod worth viewing, here It requires more calculation, but less finishing, to arrive at a true barrel shape.

Harold

You may find my pages on the subject of drill sharpening helpful Bill, it is one of the most read articles on my website. Some have written to me, and it has been said here, that they had abandoned their drill grinding jig but having read my article they found they could produce perfectly adequate results with it.

It can be seen here

Harold

If you want Nick to hold square sections using collets you may find my method of adapting round collets worth considering. Have a look here **LINK** I have used it down to 2mm square, in fact it was that requirement (making about 100 square nuts for a model cart) that made me come up with the idea.

Harold

The idea of plunging the end of an end mill into a rotating wheel is not new, I first saw it in issue 14 of MEW. I then published a more detailed version (drawings, etc.) in issue 170. This now being the subject of the link I mentioned earlier.

If you did not see my earlier comments this would have been because my contributions again went AWOL (absent without leave) for some reason, do go back a read my comments if you have missed them. Note, I will now be away from the PC for the next five weeks.

Harold

With regard to Martin's comment about a home brewed version, now to be seen in John's comments, my offer, to be seen here may be of interest to some. It is of course very much simpler but in my estimation works adequately for most home workshop tasks.

I will now be away for around 5 weeks but on my return it is my intention to start adding videos to my website and this is one of the first that I intend to attempt, my quick change lathe tool holders being another.

Harold

Seeing the test cuts taken by Owain some readers may like to visit my website where the process is discussed in depth. Do look at the photos, (6 and 7), of my similar test pieces, viewing them enlarged to view the results at the highest definition. The article can be seen here

Harold

Regarding my last post on this thread, Neil has now resolved the problem for me so no need for others to confirm having having seen it. The reason for the situation is interesting but I will not go into that.

Probably now too late for you Bruce but you may still find the articles listed on my index for MEW worth looking at.

Harold

I am puzzled, not difficult these days. On the 5th I added some comments to this thread saying that my MEW index had a section for bending rolls and listing 9 articles on the subject, most with detailed drawings. The entry followed that by Andrew which followed that by Robbo showing a copy of a page from MEW.

On the 6th I again looked at the thread only to find my contribution was not there, obviously, so I thought, I had not clicked on the "Add Posting" link.

I decided therefore to enter it again. However, needing to look back for the name of the OP I was surprised, and not a little worried, to see my contribution there all the while, how did I miss it. I therefore did not post my second attempt.

This evening, the 7th, I again found the entry was missing but on logging on it was there to be seen. I logged on and off a number of times still with the same result. When my entry is there it even then finds the number of contributions too long for a single page and starts a 2nd.

I decided as a result to view another thread I had contributed to, being "screw cutting on warco 220" again with the same result.

The system knows I have added to this thread as it sends me Emails detailing the additions that are being made to it.

Could someone just make an entry saying that they are seeing my comments, for if this does not appear I will know every one is missing them.

Incidentally, this is a copy of my original post.

If you visit my MEW index and click on Bending Rolls you will find there are 9 articles listed. I have not looked at them but from memory the one by David Fenner I think is close to what you are looking for.

Harold

Whilst it is not totally applicable to your lathe go to this page and click on the link "see explanatory drawing" (lower right of the page) and this will show what Jason and Peter have explained. The gears are though referenced as A - F rather than 1 - 6

Harold

If you visit my MEW index and click on Bending Rolls you will find there are 9 articles listed. I have not looked at them but from memory the one by David Fenner I think is close to what you are looking for.

Harold