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Boxford model A gears

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john barnes 415/07/2020 21:29:13
31 forum posts
3 photos

Hi all, I need a couple of gears for my Boxford model A gearbox. I have identified them as 16dp using the formula - number of teeth plus 2 divided by diameter. Can anyone confirm that is correct. Also does anyone know the pressure angle.

larneyin15/07/2020 23:48:03
15 forum posts
19 photos

I think the gears are 18 D.P. with a 14.5-degree pressure angle and 0.125" depth of tooth. They are 3/8" wide, have a 9/16" bore, and have a 1/8" keyway.

I stand to be corrected on this and suggest you wait for others to confirm, or otherwise

larneyin15/07/2020 23:50:34
15 forum posts
19 photos

Oops! On re-reading the post I see it is the gearbox gears you need the info for, not the change gears.

Sorry for for not reading the original post correctly

larry phelan 116/07/2020 08:26:05
769 forum posts
14 photos

You know what they say "Read twice, comment once" or something like that !!

No offence intended, Larneyin, just could not resist it ???cheekycheeky

Bazyle16/07/2020 08:45:01
avatar
5295 forum posts
201 photos

The normal changewheels are 18DP, the back gear cogs are 16DP but I've no idea what the ones internal to the gearbox are. If you have it apart try running a gear with the ones mentioned above and it should confirm either way.

Brian Wood16/07/2020 09:18:13
2206 forum posts
37 photos

If it's any help, when I overhauled my Smart and Brown Sabel on purchase, [their clone of the Southbend lathe], the gears in the gearbox were all 16 DP and at that age they would be 14.5 degree pressure angle.

I imagine Boxford followed the design in that respect as well.

Regards Brian

Edited By Brian Wood on 16/07/2020 09:18:28

larneyin16/07/2020 09:22:09
15 forum posts
19 photos

Larry

Fair comment - I can only plead advancing (even advanced) years in mitigation smiley

Tommy

William Chitham16/07/2020 09:35:54
44 forum posts
14 photos

There was a thread on this topic recently: **LINK**

William.

larry phelan 116/07/2020 14:32:41
769 forum posts
14 photos

Hi Larneyin,

Welcome to the club. The older you get, the worse it gets, trust me !, I ,m well advanced at this stage.

I need to keep two pairs of reading glasses around all the time, to be sure of finding at least one set when required, and I,m only 82 and a bit !

I hate to think what I,ll be like when I get REALLY OLD !!!laugh

john barnes 416/07/2020 17:42:34
31 forum posts
3 photos

Thanks for all the replies guys. I know the gearbox gears are definitely not 18dp because they would not mesh with my change gears when I stripped the gearbox last weekend. Unfortunately I can not try them with my back gears as Bazyle suggested because the gearbox is now reassembled and re fitted. I assumed the back gears were the same as the change gears. I am leaning towards 16dp and 14.5 degree pressure angle. I am going to try Williams link to confirm pressure angle. If I am correct does that mean I can use Myford gears. I know they will need to be adapted but they seem more readily available and much cheaper.

Brian Wood16/07/2020 18:21:04
2206 forum posts
37 photos

John,

Myford gears are 20 DP so they will definitely not mesh with the 16 DP gearbox gears.

Regards Brian

john barnes 416/07/2020 19:21:36
31 forum posts
3 photos

Thanks for that info Brian. I have had a quick look for the gears that I think I need. One in particular seems very uncommon. It may be cheaper and quicker to make my own.

not done it yet16/07/2020 23:31:00
4747 forum posts
16 photos

Raglan and Drummond, amongst others, used 16DP with 14.5 PA change wheels. Presumably they would need keyways cutting, if hard enough. Both were 16mm bore and 3/8” thick, I think.

Give us a clue of tooth count required?  And any other pertinent detals.

Edited By not done it yet on 16/07/2020 23:31:46

Keith Long16/07/2020 23:40:26
838 forum posts
11 photos
Posted by not done it yet on 16/07/2020 23:31:00:

.........Drummond, amongst others, used 16DP with 14.5 PA change wheels.

No, Drummond used 14DP with 14.5 deg PA.

john barnes 417/07/2020 18:00:21
31 forum posts
3 photos

I have been searching for gears using Boxford as a keyword but I am going to omit Boxford from my searches from now on just in case there is another maker such as Raglan or Drummond using 16dp gears. The gear I want to replace is a 16 tooth / 32 tooth combination. I also have a couple of 32 tooth gears showing signs of wear which I will change if I can find them cheap enough or can find the cutters I need to make them. The gearbox was dismantled and all gears cleaned and deburred where necessary, oiled and replaced. It is working better than it was but when the 16 / 32 combination is selected it sounds noisy and feels rough. I wish I had taken pictures of the strip down so you could see the damage but it did not occur to me.

Brian Wood18/07/2020 08:59:07
2206 forum posts
37 photos

Hello John,

Here's a suggestion.

There are two combination gears [16/32 teeth] in the doubling gearing part of the gearbox. The noisy one has perhaps had a lot of use and you could perhaps put off the day when action has to be taken by swapping them over

Regards Brian

john barnes 418/07/2020 11:25:30
31 forum posts
3 photos

Hi Brian, I am not absolutely sure but I think one pair of gears is keyed and the other pair not. I tend to avoid using the bad gear unless I need it for screwcutting.

John

Brian Wood18/07/2020 16:32:19
2206 forum posts
37 photos

Hello John,

You could well be right, it is several years since I rebuilt the Sabel gearbox and I could easily have forgotten that small but important detail.

Sorry if I have raised your hopes prematurely

Regards Brian

john barnes 418/07/2020 19:39:50
31 forum posts
3 photos

No need to apologise Brian I welcome your input.

John

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