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Pulley needs a keyway, Toronto area

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WCraig

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#1
I want to get a keyway broached into a cast iron pulley. It was formerly mounted on a different motor that has a flat spot on the shaft and was secured with just a couple of set screws. I've moved up from a quarter HP to one-half and the new motor has a standard 3/16" keyway.

I looked into buying a broach set but the least expensive option seems to be over $300 Canadian.

Is there a member in the GTA West that could help with a job like this?

Alternatively, is it possible to get "half-height" key stock? That way, I could make a 'flat' on the motor shaft and tighten the pulley set screw on that.

Craig
PS This is for my Atlas 618 resurrection. I am oh-so-close now!
 

Bob Korves

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#2
Find someone in your area with a shaper, or slotting attachment for a mill, or a broach and press to cut it for you. They will have it done in no time. That is an very common job at machining job shops. A keyway can be done with files, but it takes patience, skill, patience, and time to make one that fits snugly along the entire length and all sides of the key. It can also be done with a simple setup on a lathe, operating like a shaper. The lathe motor does not need to be operational to do it. It is relatively slow but gives good results if done properly:
https://www.youtube.com/results?search_query=cutting+a+keyway+on+a+lathe
 

Asm109

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#3
A boring bar with a 3/16 inch square bit will make a fine broaching tool.

Mount the pulley in the 4 jaw chuck and indicate it in.

Mount the boring bar in the tool post. Adjust height so it is dead on center of the bore.

Lock the spindle in back gear so it won't rotate.

Run the carriage up and down the bed to act like a shaper ram.

dial the cross slide out a thou or two at a time. It takes a while but it doesn't cost anything for tooling.
 

francist

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#4
If your pulley is indeed cast iron I would be careful if trying to use the 618 to single-point broach the keyway. I've done this on my 618 in softer metals and yes it does work, but it's a bit of effort for the small rack and gear on the lathe. I don't know if I'd want to risk it in cast iron. Might be ok,, but then again...

As for half-height key stock -- it's just mild steel. File it, grind it, or sand it to half-height yourself. It is not hardened material.
Alternatively, a dog-point set screw may settle in to the keyway in the motor shaft and not gibble up the shaft.

-frank
 

WCraig

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#5
I was aware of that technique of using a boring bar like a shaper. Unfortunately, I don't yet have a boring bar.

For now, I've gone ahead with the half-height key idea. I think a proper key is a better long term solution but this gets me moving forward for the time being.

For those that like action shots...

I put a piece of key stock in the slot in the motor shaft and marked the height. I then channeled my inner Konrad Sauer cut to the line. Since it only takes about 9-10 strokes with the hacksaw, I acted like I was cutting a dado in wood--lots of kerfs!

half-key_1.jpg


I then used a rasp to waste the remaining bits:

half-key_2.jpg


After that, I snuck up on the fit. At the end, I could not hold it in the vise anymore so I clamped the long tail to my drill press table. I used calipers to check the size at various points, coloured with marker and filed to fit. I used a diamond sharpening plate to knock of the burrs and round the top corners slightly. Eventually it fit and I cut off the tail.

half-key_3.jpg


The butchered key is a very snug fit with the pulley on the shaft. In a couple of quick tests, the set screw seems to be holding but I would still rather have the keyway cut into the pulley. I like to run with the belts just a little loose so that if something bad happens, they'll slip. I'd rather that than having the pulley spin on the motor shaft and the set screw cause galling.

Craig
 

WCraig

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#6
If your pulley is indeed cast iron I would be careful if trying to use the 618 to single-point broach the keyway. I've done this on my 618 in softer metals and yes it does work, but it's a bit of effort for the small rack and gear on the lathe. I don't know if I'd want to risk it in cast iron. Might be ok,, but then again...
Indeed. The half-height key was about 0.100 so the keyway must need to be broached to about the same depth. I was figuring that a 2 thou depth of cut might be safe. That would be something like 50 passes!! Maybe more!

Craig
 

MrWhoopee

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#7
Just get some full-dog (extended tip) set-screws (add an extra if there's only one over the keyseat and space allows) and drive them down into the keyseat. https://www.mcmaster.com/set-screws
 

WCraig

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#9
Check the accusize industrial catalog they have individual broaches 3/16 is $ 40.00 Cdn. You can make the bushing to fit your bore no need to spend 300.00
http://accusizetools.ca/products_details.asp?big=3&small=10&proid=513.
There just down the road from you on Beaver Creek Road.
Thank you, I hadn't run across Accusize before. Looks like they have some inexpensive stuff. However, it looks like the company deals with distributors while they sell direct through their eBay store.

Craig
(BTW, their Richmond Hill location is about an hour's drive for me. Depends on your definition of 'just down the road'!)
 

aliva

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#10
I've bought a lot of tools from Accusize. Direct from their web site. You don't have to go thru the eBay store. As far as I know all of their tools are from Taiwan or India. I've been very satisfied with all of my purchases. Download their catalog some very interesting products and prices. Due to the ongoing postal dispute, I would pick up the product from their warehouse, in Richmond hill. or pay for courier delivery ( could be expensive)
BTW " just down the road" in northern Ontario is anything under an hour and half drive.;)
 

Bi11Hudson

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#11
Worst case RIGHT NOW is a couple or three hacksaw blades and a three square file. Slow, but works well enough. This has been the fall back since my grandfather's time. (1890)
 

mmcmdl

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#12
Do you have an arbor press ?
 
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