Gear woes

[mikemm]

I recently acquired a B & S #2 surface grinder as a candidate for restoration. Most of the work needed is minor in nature, however I have realized that the table drive pinion gear and intermediate gear are severely worn with massive backlash. The rack on the underside of the table seems ok from a visual inspection.
I contacted Bourne & Kotch to inquire about replacement gears only to have them quote me about $2400.00 for the 2 gears. I figured the OEM is always going to rape you on prices so I contacted a commercial gear maker called rushgears. They quoted a whopping $4,000.00 for the 2 gears making the OEM seem like a bargain.

I calculated from the OD of 1.7 inch and 3.7 inch and number of teeth they are 10 DP 15 tooth steel and 35 tooth cast iron spur gears with a 1 inch face width.
I have a bridgeport and a lathe and after watching some youtube vids, I think I might be able to make the gears myself. The material cost from online metals is around $35.00 and I'm confident I can turn and bore the blanks pretty easily. I have never made a gear as I don't have the required tooling.

There was no way to measure the pressure angle from the worn gears so I turned a gauge plug with a 29 deg taper and a 40 deg taper on an aluminum rod using the lathe compound and fitted them to the rack. the 29 was almost a perfect fit in the rack so I can safely assume a 14.5 deg pressure angle.

I'm putting together a list of things I would need for this project. I have a precice 12 inch rotary table but with the odd number of teeth I think I'll be better suited with a dividing head which I don't have yet, I'm looking at a Taiwan made, not Chinese B&S 0 head with tail stock. It's about twice the price of the Chinese one. Will this be rigid enough for the job or would I need a B&S 1 head?

I will also need a 3/4 and 1 inch mandrel, an R8 stub arbor and I think a #3 and #7 10DP cutter for the teeth ranges on each gear.
I also need a broach setup for the small gear to cut 2 keyways.

so far I'm looking at about $800.00 in tooling alone. If I have to go for the larger dividing head then we are closer to $1100.

What's my probability of success? I would hate to dump this money and have it not work out

Any thoughts, recommendations?

Thanks

 

[Joeman77]

You might look into Mcmaster-Carr, they've got quite the selection of gears, then all you've got to do is bore & broach for keyways.
As an alternative I've heard of the whole rack & pinion assembly being replaced with a cable & sheave, that way you don't have extra vibration induced influencing surface finish of the part by the gears. This is the one I'm considering when I get time for my old Reid surface grinder.

 

[DavidR8]

You might try these folks also.

Any Gear Made Quickly Inexpensively & Perfectly Al Meekins GearsMade.com. --Delrin gears Plastic gears Bevel gears Worm gears Spur gears Helical gears Phenolic gears Stainless steel gears Cast iron gears Machine gears Steel gears Metric gears Bronze

Sent from my iPhone using Tapatalk

 

[tazzat]

Can you use this? and just modefy to fit.

15 tooth 10DP Steel Spur Gear (SSDP10/15B) [SSDP10/15B] : Beltingonline.com, Supplier of power transmission and conveying products

Beltingonline.com 15 tooth 10DP Steel Spur Gear (SSDP10/15B) [SSDP10/15B] - Spur Gears 10 DP - 20° p.a. Steel EN8, 080M40/080M46

www.beltingonline.com

35 tooth 10DP Steel Spur Gear (SSDP10/35B) [SSDP10/35B] : Beltingonline.com, Supplier of power transmission and conveying products

Beltingonline.com 35 tooth 10DP Steel Spur Gear (SSDP10/35B) [SSDP10/35B] - Spur Gears 10 DP - 20° p.a. Steel EN8, 080M40/080M46

www.beltingonline.com

 

[Lo-Fi]

I've just set myself up a decent gear cutting rig - happy to knock them out a couple of gears for you if you like? Shipping won't cost much wherever you are in the world! Gears that size are well within my capability, though I'd have to get 10DP cutters in.

I really like making gears

 

[cathead]

A photo of your dilapidated gears would be a big help here. I have made a lot of gears with a 12 inch rotary table
using dividing plates on my vertical mill and have been well satisfied with the results. You do not need a dividing
head, just a bit of tooling to get started. The RT will make any gear tooth count and is plenty rigid for the job so it
looks to me like you are close to making some chips.

 

[mikemm]

Here are some pictures of the existing gears

 

[mikemm]

DavidR8, thanks for the link I will also have them quote me. I cant see it being reasonable though based on the other quotes.
Tazzat, those are 20 degree pressure angle. looking for 14.5 degrees.
Joeman77 I have actually found some similar gears at MRO supply. better selection than McMaster.
The 15 tooth is very close, I would just need to broach a second keyway and reduce the hub projection.
Problem is the 35 tooth. my original is cast iron and this one is steel. I recall Keith Rucker in one of his videos saying its better to have 2 different materials on mating gears. Opinions on that?
First problem is I can't find 35 tooth cast iron. Second problem is the original gear has a second protruding hub (type C gear). I can always use a 1/8 thrust washer to position the gear correctly. Third problem is the bore is 3/4. I need to enlarge it to 1 inch to press in the bronze bearing. How do I grip a finished gear in a lathe and indicate the 3/4 bore and true it out to 1 inch. Much easier to bore a blank to 1 inch and then press in bearing and mount blank to mandrel and cut gear on centers.
Cathead, not following the use of dividing plates on RT. My table is Yuasa and does not have provision for dividing plates. The angle for the 15 tooth is 24 degrees which is super easy. The 35 tooth is 10.28571428571429 degrees and next to impossible to dial in.
Lo-Fi, thanks for the offer. I just might take you up on that if it proves impractical for me to try to make them. are you in The US? I'll PM you if I go that route.

 

[JimDawson]

As an alternative I've heard of the whole rack & pinion assembly being replaced with a cable & sheave,

What @Joeman77 said ^^^^^^^^

Or use a timing belt. Also look at the Boston Gear catalog to find the replacements, that looks like maybe a couple hundred bucks worth.

 

[Lo-Fi]

I'm UK based, but shouldn't be a big deal shipping a couple of gears anywhere.

Could go steel for one and bronze for the other? That's probably an even better combo than steel and iron. Even plastic would probably work nicely for that application, though.

Gripping off the shelf gears to bore the centre is best done with a cup arbor cut specifically for the job if the size and tooth count doesn't lend itself to being directly held in inside chuck jaws.

I'm in the process of cutting a load of change gears myself to fit my dividing head. I want to have some fun setting it up to cut helical gears.