View Full Version : Need suggestion for gears wtih specific keyed hub..

07-05-2015, 10:10 AM
My Jet 1440 3PGH

Many of you, particularly His Lordship and Arthur Marks.., helped me understand my gear chart. I have taking out the gearing its it appears to be a hodge podge. Here is a reference to the thread with the chart http://bbs.homeshopmachinist.net/threads/64993-Thread-chart-help-on-lathe

So I am trying to find gears that work. Here is a picture of the hub spline.. they only go on one way....

http://i201.photobucket.com/albums/aa129/xringx/20150705_092517_zpsx8aem4y1.jpg (http://s201.photobucket.com/user/xringx/media/20150705_092517_zpsx8aem4y1.jpg.html)

I need a 54 tooth and a 56 tooth gear

07-05-2015, 11:53 AM
That's very similar to my 14x40 (TUM35). Measure the spines - being JET... maybe din standard metric. expressed like 21x24 (inside to outside of splines) I have to make 13 -15 gears so I can cut a range of metric threads.... grumble..

I could not find a USA source for my gears. One said USA, but simply has them made in Japan at stupid $$. I did find a UK seller, but last I checked would cost me about $1500. So... I'll be figuring out how to do it myself.

There is a very expensive progressive broach that will do it in one pass, or... use a manual single indexed broach (one cut slot, then add an offset slot for a key to locate the second). Or shaper or I might use my cnc mill to cut the keyways with a shaper tool (might be a bit rough hard on the spindle bearings).

For just two gears.. have you contacted JET?

John Stevenson
07-05-2015, 12:20 PM
Read post # 74 in this thread for the splines.


07-05-2015, 12:45 PM
Read post # 74 in this thread for the splines.


Your Lordship...

I read it.. My basic take away (i am not a machinist) is that you converted it to a quieter belt drive..which is nifty..but dosnt get me to cutting threads... AND, if the reference to the thread was on cutting the spline myself.. I think i would just rather do something to achieve the results. I do have 2 keyed spacers, which are pretty long so I could in theory mary them to new gearing..

07-05-2015, 01:02 PM
I think you meant this..."If you work the compound train out of the other ratio, not shown, it works out to 21 driving a 72." Did I also say I suck at math? Hence.. poor machinist??

I think I get what you did..let me see if I can work something out...

Ok,, working with my kid, and we have looked math.. particularly here http://www.schsm.org/html/gear_ratio_calculations.html

And it seems to me, that in the end, that to accomplish what John did, he just worked out the speed ratios to be similar to the original.

So the question we have, and cant find on the internet, how important are the teeth vs the diameter of the gear? All this teeth business is just fluff, it its really the gear diameter and the teeth is just the mating technology and defining difference since no belt is involved....

Ok,, EDIT.. Not removing what I said.. but a hot shower has cleared my mind, and the above is probably hog wash.. there has to be something to the teeth.....I am working on it..

07-05-2015, 02:55 PM
Very important! If they are metric it's pretty easy. Find the module first - probably 1 or 1.5.

07-05-2015, 02:55 PM
Ok, this is where my son and I ended up.

Per my chart, I am supposed to use a 58t, to a 82t slaved to a 54t driving a final gear which is 56t. Using the formula on the website I listed, with 100rpm, we get a final rpm of 68.2 on the 56t gear.

07-05-2015, 03:08 PM
cuemaker - I think you missed the "post 74" part?

He took a standard push broach (like is used for a single keyway) and made a custom sleeve (the part which is inserted into the hole and has a slot to guide the broach). He surface ground the width of the broach to match what he needed. This is the one part where you might have trouble if no surface grinder is in your shop.

The sleeve guide was made with an approriate depth of slot to end up with a correct spline tooth depth after the broach is pushed through. He then put a hole an 1/8th of a full rotation from the slot in the guide sleeve. This allows a short pin to be inserted and locates the sleeve rotationally from the previously cut slot. After using the broach eight times, he has created an eight-tooth spline around the hole.

In other words, he used a single, modified broach for a single keyway. But made a way to properly orientate it to create eight identical, properly spaced keyways around a hole: a spline.

Yours, of course, only needs six teeth instead of John's eight. The width and depth of each tooth is also going to be different. The process, though, will be identical given those changes.

07-05-2015, 06:05 PM
You only need one key unless you are intending to do some heavy handed production work. So just bore the hole to the outer diameter and hand file a single slot in the bore. Then file a mild steel key to go in your slot and the shaft. If it is too sloppy make another. Locktite it in place. In a year or two when you are more experienced you will know how to broach some more slots and make better keys from harder stuff, if you really need to.