Author Topic: keyways.  (Read 2004 times)

Offline wheeltapper

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keyways.
« on: September 30, 2016, 08:44:43 AM »
I am in the process of converting my mini mill to belt drive.

I've made the small pulley apart from the keyway.

the bore is 9mm dia by 25mm long , deep ,whatever,, the keyway needs to be 118 thou wide.

how the heck do I cut this without a keyway broach which I haven't got and can't afford.

I've also got the large pulley to do when I've made it.

answers on a postcard  :).

cheers

Roy.
I used to be confused, now I just don't know.

Offline Joules

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Re: keyways.
« Reply #1 on: September 30, 2016, 08:54:27 AM »
Setup a jig that will let you hacksaw slots parallel or drill, then use a fret saw to cut out the remains and file to size.  Otherwise have you anyone close by with a shaper.
Just get doing and make swarf, you can decide what its going to be later.   :thumbup:

Offline John Rudd

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Re: keyways.
« Reply #2 on: September 30, 2016, 09:14:04 AM »
Roy,
I did exactly the same thing, convert my mini mill to belt drive.....
However I didnt key the pulley.....I left that as a weak point...so the pulley relies purely on the tightish fit on the shaft and the retaining screw in the end of the motor shaft....

Should anything go badly wrong, hopefully either the belt or pulley will slip.....

As for the bigger pulley, I jury rigged a boring bar in the  lathe with a tool steel cutter ground up to cut the keyway....then use the saddle back n forth increasing depth with each pass.....Worked for me... :dremel:
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Offline wheeltapper

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Re: keyways.
« Reply #3 on: September 30, 2016, 09:30:22 AM »
Thanks for the ideas guys.

John, would this work on the small one, remove the key and replace it with a shallower  aluminium one so the surface is level with the shaft, the use a pointed grub screw into the ali.

I was thinking about your idea for the big one, there's more room.

cheers
Roy.
I used to be confused, now I just don't know.

Offline Will_D

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Re: keyways.
« Reply #4 on: September 30, 2016, 09:40:17 AM »
I turn down the end of a grubscrew till its the width of the keyway, then drill and tap the pulley.

If has to be bitted in the Belt groove then make sure the overall length when tightened is correct i.e.  the head is just bellow the bottom of the belt.
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Offline Jasonb

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Re: keyways.
« Reply #5 on: September 30, 2016, 09:49:26 AM »
You can do it in the lathe. Use a boring bar that takes a HSS toolbit and grind that so it looks like a parting tool but mount it so the cutting edge is vertical not horizontal.

You then just wind the carrage along and plane a small amount off,withdraw add a tho or two cut and repeat until you are at the required depth.

If its aluminium it will be quite easy going, I have done upto 3/16" wide in steel but that takes some effort.



As your hole is quite small it may just be easier to hold a bit of 3mm square toolsteel in the toolpost and run that in as above, bit like this




Offline Lew_Merrick_PE

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Re: keyways.
« Reply #6 on: September 30, 2016, 11:45:28 AM »
My "solution" is simple.  I go to one (of the five) machine shops within 10 miles of my shop with a box of doughnuts and a gallon of juice (and a $10 bill) an politely ask them to "slide in" my keyseat part when next they set-up for broaching keyseats.  The longest "turn-around" has been a week-and-a-half as they were going into "summer shut-down" the next (it was a Friday) week.

All bribes are to be paid in Coin of the Realm.  The only problem is determining which Realm and what Coin.

inthesticks

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Re: keyways.
« Reply #7 on: September 30, 2016, 12:42:28 PM »
Jasonb that is an excellent solution and true to the classic home machinist theory that a good lathe in the absence of other machine tools and with a little bit of creativity can do any procedure required by the home machinist.

Cheers CB

Offline drmico60

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Re: keyways.
« Reply #8 on: September 30, 2016, 12:49:05 PM »
Wheeltapper, It is easy to make a simple tool that can cut keyways in small diameter holes,see:
http://mikesworkshop.weebly.com/small-hole-slotting-tool.html
Mike

Offline krv3000

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Re: keyways.
« Reply #9 on: September 30, 2016, 05:47:47 PM »
hi I have dun in the past watt has just bin told make a tool up that looks like a parting off blade and fit it in to the tool post  and just for thows that don't no the rule of thumb the slot shod be  divided by two so if you is say  is you sing 10mm key way steel then the slot in the shaft will be 5 mm deep and the one in the pulley will be 5 mm deep and for a bit of fun you shod you all ways youse key way steel for key ways 

Offline mexican jon

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Re: keyways.
« Reply #10 on: September 30, 2016, 08:09:49 PM »
I am in the process of converting my mini mill to belt drive.

I've made the small pulley apart from the keyway.

the bore is 9mm dia by 25mm long , deep ,whatever,, the keyway needs to be 118 thou wide.

how the heck do I cut this without a keyway broach which I haven't got and can't afford.

I've also got the large pulley to do when I've made it.

answers on a postcard  :).

cheers

Roy.

Is it really 118 thou  :scratch: or is it 3mm  :scratch:

The small pulley normally has a 9 mm bore with a 3 mm keyway. The large pulley has a 30 mm bore with a 5 mm keyway

You are only up the road from me (I'm in Great Yarmouth) you would always be welcome to borrow the use of my Broaches  :thumbup: I have a fairly comprehensive selection of Marlco's.
« Last Edit: October 01, 2016, 06:26:03 AM by mexican jon »
People say you only live once ! I say thank F@*K can't afford to do it twice.

Offline wheeltapper

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Re: keyways.
« Reply #11 on: October 01, 2016, 07:00:22 AM »
Hi Jon
yes they are 3mm and 5mm , its just that the plans I have are in imperial and I prefer thous.

thanks for your kind offer however (1) I dont have a press. (2) I'd be scared of breaking them. and (3) getting anywhere in that direction is a nightmare with all the NDR roadworks.

thanks anyway, I'll bodge something. :lol:

cheers
Roy.
I used to be confused, now I just don't know.

Offline Will_D

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Re: keyways.
« Reply #12 on: October 01, 2016, 05:15:22 PM »
You can do it in the lathe.
Great photos Jason

Are you using a macro lens?
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Offline Jasonb

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Re: keyways.
« Reply #13 on: October 02, 2016, 02:55:32 AM »
Just a little Sony cybershot for the second pic and the other one was a while ago on a Minulta Dimage 7, both just on auto and let them do their thing.