Nige | 10/08/2017 15:28:08 |
![]() 370 forum posts 65 photos | Help please! I am trying to set the ML4 up to cut 26 TPI (1/4 BSF) I have the screw cutting table, photo below, but I am confused in identifying the various wheels under the column headings. I'm not sure which is the Mandrel gear, I'm guessing it is the one with a 25 tooth gear shown in the second photo below. The first stud I believe is the one that currently has a 50 and 20 tooth gear on it and the 2nd stud has the 55 tooth with a 20 tooth behind? The only thing I am sure of is the 65 tooth lead screw gear which is the correct one anyway. I believe the 'idle wheel' needed on the 1st stud (from the table) is a 20 tooth gear but 1st stud has two gears on it at the moment one of which is a 20 tooth, what do I replace the 50 tooth on that stud with? For the 2nd stud the table is blank, does that mean the 2nd stud has nothing on it? I am completely at a loss as to what is going to go where !!! |
Jon Gibbs | 10/08/2017 15:43:03 |
750 forum posts | Hi Nige, The ML7 handbook in pdf can be downloaded from here **LINK** Pages 25, 26 and 27 show the same nomenclature to help with your setups. HTH Jon |
Russell Eberhardt | 10/08/2017 15:53:17 |
![]() 2785 forum posts 87 photos | I don't think the table you have is the right one for your lathe. Yours has a tumbler reverse which changes things a bit. The mandrel gear is the one mounted on the rear of the spindle which in your photo seems to be another 25 tooth gear. You can't change that unless you remove the tumbler. The tumblers just act as idlers so don't change the ratio. The gaps in the table are where idlers should be fitted. They just transfer the drive from one gear to the next without changing the ratio. They do, however, change the direction. You will need to calculate the gears required yourself or use a simple program such as NthreadP which can be found on the lathes.co.uk website. Russell
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Nige | 10/08/2017 16:41:34 |
![]() 370 forum posts 65 photos | Thanks Jon: It looks as if the gear they term 'Mandrel' is the interchangeable gear on the end of shaft that also carries the Tumbler reverse gear. Those diagrams in the ML7 handbook make things a bit clearer its a shame they didn't do that level of information in the ML4 booklet which is where the Screw cutting table comes from. Ill go and have a look see. Russell: Thank you. As mentioned above the table comes from Myford sales booklet for the ML4 which is very short on other useful info! Fortunately it looks like the ML7 Handbook is similar enough to get me where I need to be |
JasonB | 10/08/2017 16:43:42 |
![]() 25215 forum posts 3105 photos 1 articles | 25T on the spindle drives a 20T on the tumbler/mandrel = 1.25 That 20T drives a 25T on stud 2 via anything on stud 1 = 0.8 Another 20T driver on stud 2 drives a 65T on the leadscrew = 0.307 1.25 x 0.3 x 0.307 = 0.307 8tpi leadscrew gives 0.125" per rev So 0.125 x 0.307 = 0.0384" 26tpi = 0.384"
Simples
Edited By JasonB on 10/08/2017 16:44:02 |
JasonB | 10/08/2017 16:48:30 |
![]() 25215 forum posts 3105 photos 1 articles | So change the 25T on the tumbler for a 20T remove the 50T and 20T from stud No1 and fit a fit something that fills the space remove the 20T and 55T from stud No2 and fit 20T & 25T leave 65T on the leadscrew |
Nige | 10/08/2017 17:59:15 |
![]() 370 forum posts 65 photos | A bit of confusion introduced by referring to the ML7 Handbook as it says I would need an 'Idle 70 wheel' which suggests the need for a 70 tooth gear which I don't have. The table from the ML4 booklet only refers to an 'Idle Wheel'. I finally phoned Tony Griffiths of lathes.co.uk asking what the equivalent gear is on the ML4 and he explained that in this instance the 'idle gear' can be any spare gear I have that I can adjust to fit in the space between the driver and the driven gears. back to the lathe after tea JasonB: Thank you, only just seen your post which will do the job as well Edited By Nige on 10/08/2017 18:02:40 |
Brian Wood | 10/08/2017 18:29:37 |
2742 forum posts 39 photos | Nige, |
Howard Lewis | 10/08/2017 18:31:18 |
7227 forum posts 21 photos | As long as the "idler" wheel can be meshed with both the gear on the Leadscrew and the compound "driving" pinion, within reason, it does not matter how many teeth it has. It is just there for fill the space and transmit the drive, without affecting the overall gear ratio, but one Idler will reverse the direction of rotation, so you may need to use the tumbler to ensure that you cut a R H thread rather than a L H! later, you will probably be able to buy, or even (with help) make any gears that you need. Myford gears are 20DP, but can't remember whether the Pressure Angle is 14.5 or 20 degrees. Someone will confirm. Dealers such as Home and Workshop Machinery in Sidcup usually have a selection of gears for the Myford. A plea on the "Wanted" section of this Forum may find what you want. If not prowl around Shows, looking for what you want. Final thought, would it be easier to buy a length of 1/4 BSF studding from somewhere like Cromwell Tools? Howard Edited By Howard Lewis on 10/08/2017 18:32:22 |
Neil Wyatt | 10/08/2017 19:10:01 |
![]() 19226 forum posts 749 photos 86 articles | The three gears on the reversing stud are all idlers and have no effect on the gear ratio at all, except changing the direction of rotation. Neil |
Robbo | 10/08/2017 23:13:30 |
1504 forum posts 142 photos | Quote "later, you will probably be able to buy, or even (with help) make any gears that you need. Myford gears are 20DP, but can't remember whether the Pressure Angle is 14.5 or 20 degrees. Someone will confirm." 14.5 degrees. |
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