What motor pulley size for ML1 Lathe?

[Chris VParticipant @chrisv]

Thanks for that Not Done it Yet, good food for thought!

Cheers

Chris.

[not done it yetParticipant @notdoneityet]

Hi Chris,

I’m not a machinist, so I take the easy way if I can find it. Threading is easy on the lathe but good taps/dies can provide a more accurate thread form – more accurate thread angle and proper shape at peaks and troughs (but not always that important).

As a beginner, you will often find there is a better way than the one you first thought of! Even drilling a hole of particular size may not be as simple as selecting a drill for the job. Hence the saying about not knowing whether something is punched, bored or countersunk… you could add to that reamed, counter-bored and even spark eroded.

[Chris VParticipant @chrisv]

Thanks for the encouragement Not done it Yet, yes I was thinking it would be easier…but its a way down the road yet, I need to get it up and running first!

Cheers

Chris.

[Howard LewisParticipant @howardlewis46836]

Being a thorough coward, I avoid messing about with changewheels, etc, unless I have to, So for threads of 1/2" or 12 mm and under, wherever possible, I use Taps and Dies. They will, or should be, ground more accurately than I could a single point tool.

Dies are used in a holder, which slides (Plenty of clearance to allow the Die to follow the workpiece, to avoid "drunken" threads ) on a an Arbor in the Tailstock

If the length exceeds that of the Die Holder, once the thread has been started, the die could be allowed to continue, off the arbor, prevented from rotating byb the arm resting against the toolpost. There is the risk, that the torque could shift the holder and produce a drunken thread. But that is a risk almost inherent in holding the Die in a holder which is no longer limited by the Holder / Arbor clearance, which prevents things getting too far out of line. I have seen pictures of a Die being held in a holder with along arm resting against the Saddle or bed.

may be, once the thread has been started the Die could be held in a holder, centred, and clamped in the Toolpost. I have never tried this, so it is subject to practical evaluation!

For taps, I made up a similar Arbor, and hold the Taps with ER 25 Collets in the Holder.

Making a such a Holder will give you a problem, since the thread for ER collet nuts is 32 x 1.5 mm. which is likely to be within the gear set for a M type.

Howard

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Edited By Howard Lewis on 07/10/2019 18:37:13

[Chris VParticipant @chrisv]

Thanks Howard, certainly for the foreseeable Im sure a tap in the tailstock chuck will suffice. Just thinking about the die in the toolpost idea I can now see both the spindle speed and feed speed would have to suit the thread, so I may as well go the whole hog and screwcut under power or use the tailstock facilities.

Looking at gears on the well known auction site I see some listed for Myford even with the pin link holes are apparently a different pitch so not all say 65T gears are the same and may not mesh together…?….

[Howard LewisParticipant @howardlewis46836]

AS an alternative to my ER chuck sliding on the arbor, you could fix an ordinary drill chuck onto a piece of bar that slides along the arbor. Takes a bit more space, but makes life easier and has benefits.

The assembly will need to be prevented from rotating, so the bar needs to be drilled and tapped, so that a an arm (a short piece of M8 stud? ) can rest against the Toolpost.

This sort of arrangement has the additional advantage that if the torque becomes too high, the tap slips in the holder, rather than breaking!

Howard

[Brian WoodParticipant @brianwood45127]

Hello Chris,

I feel sure I am correct in saying that Myford change wheels have always been 20 DP and 14.5 degree pressure angle, with or without the link pin hole that was a feature of the earlier change wheels. That was replaced by the stronger 1/8 inch keyway on the ML 7.

The later design can still be used of course but you will have to drill the link pin hole. Before I parted with my late father's ML 4 I had made a simple drilling jig located from the bore of the gear to get the pin hole in the right place, it went with the lathe to the new owner.

20 DP gears will not mesh with pitches other than 20 DP; changes in pressure angle [ for example 14.5 and 20 degrees, the more modern angle in use] also affect the meshing but for low speed and infrequent use, whilst not being good practice can be tolerated.

Regards Brian

[Chris VParticipant @chrisv]

Thanks Howard, just checking I understand you, your last sentence re tap slipping, if it did it would be slipping within the chuck?

Cheers

Chris.

[Chris VParticipant @chrisv]

Hi Brian, thank you.

What does DP stand for please?

Thank you for the jig idea, sounds like a good plan! (-:

Cheers

Chris.

[Howard LewisParticipant @howardlewis46836]

Hi Chris

Firstly, Yes, it is better that the Tap slips within the drill chuck, than being broken.

Often a Tap will slip in the chuck, but the thread can be completed by slackening and withdrawing the chuck, and replacing it with a tap Wrench. You can then continue tapping, being able to feel the load on the tap. With larger sizes, say 8mm / 5/16" upwards this can be great enough to cause a Tap to slip, without there being a problem.

This is at least "fail safe"

Obviously, when using a Tap Wrench by hand, it is important not to cause any side (Bending ) load on the Tap – That way lies disaster to both the Tap and the workpiece!

With regard to gears, DP means Diametral Pitch, which is the ratio between the size of the gear, and the number of teeth. A 20 DP gear with 20 teeth will have a diameter of 1.1" The formula is: OD = (N+2 ) / DP

Module gears, being Metric, are the same, but using mm instead of Inches, as the unit of measurement.

The Pressure Angle affects the exact shape of the tooth, so meshing 14.5 and 20 degree gears is a very bad idea, which will, at least, wear both gears, even if the DP is the same

Myford gears are 14.5 degree P A, where nearly all modern gears are 20.

Ivan Law's book, "Gears and Gear Cutting", No 17 in the Workshop Practice Series, will explain a lot more about gears ever than I can.

HTH

Howard

[Chris VParticipant @chrisv]

Hi Howard, thanks again, this is most helpful & useful info!

Cheers

Chris.

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