Grub screws

Topics include, Machine Tools & Tooling, Precision Measuring, Materials and their Properties, Electrical discussions related to machine tools, setups, fixtures and jigs and other general discussion related to amateur machining.

Moderators: GlennW, Harold_V

Geochurchi
Posts: 153
Joined: Mon Feb 22, 2021 7:49 am
Location: Concord ,NH / Naples, Fl

Grub screws

Post by Geochurchi »

Hi All, looking for an easy way to install a Lovejoy coupling on to a shaft with minimal tools , I am thinking of drilling a small hole into the shaft so that when I install a Grub screw into the coupling it would have a better grip.
Any thoughts?
Geo 🇺🇸
If it ain’t broken keep working on it until it is .
Geo 🇺🇸
Russ Hanscom
Posts: 1955
Joined: Wed Mar 15, 2006 11:10 pm
Location: Farmington, NM

Re: Grub screws

Post by Russ Hanscom »

A keyway is a far better bet. If you have only light loads, might get away with your plan, but not recommended. You do not mention shaft size. For a small shafts, a through pin is acceptable, for larger shafts, definitely a keyway.
Geochurchi
Posts: 153
Joined: Mon Feb 22, 2021 7:49 am
Location: Concord ,NH / Naples, Fl

Re: Grub screws

Post by Geochurchi »

Hi, shaft is probably 1/2” to 5/8” , not much load just an alternato
C9A1EB89-31E5-41D1-9A93-C414C4A41634.jpeg
r, see pic.sorry I can’t seem to turn the pic around.
If it ain’t broken keep working on it until it is .
Geo 🇺🇸
User avatar
liveaboard
Posts: 1971
Joined: Sun Dec 08, 2013 1:40 pm
Location: southern Portugal
Contact:

Re: Grub screws

Post by liveaboard »

That looks like a beefy alternator; 80A or more?
The torque is surprisingly high on that type of thing. I used to burn up V belts until I went to dual belts.

I I suspect a grub screw will fail.

A trick for people without the means to cut keyway grooves; Drill a hole along the shaft and hub, basically creating a round keyhole.
Tap it.
Then you can put your grub screw in, but the entire length with be on shear.
I usually drill a larger hole to countersink an Allen screw head. I use a drill smaller than the screw head, then cut the screw head down on the lathe for a snug fit.

For really high torque, I've used 4 screws.
This hub swings the boom of my hedgecutter, it's turned with a 10 ton hydraulic ram on a lever.
The screws are 14mm (9.16")
pivot plate and lever.jpg
Geochurchi
Posts: 153
Joined: Mon Feb 22, 2021 7:49 am
Location: Concord ,NH / Naples, Fl

Re: Grub screws

Post by Geochurchi »

Thanks for that suggestion
If it ain’t broken keep working on it until it is .
Geo 🇺🇸
John Hasler
Posts: 1852
Joined: Tue Dec 06, 2016 4:05 pm
Location: Elmwood, Wisconsin

Re: Grub screws

Post by John Hasler »

liveaboard writes:
A trick for people without the means to cut keyway grooves; Drill a hole along the shaft and hub,
basically creating a round keyhole. Tap it. Then you can put your grub screw in, but the entire
length with be on shear.

This is referred to as a "Dutchman" for some obscure reason. I've used it successfully.
User avatar
liveaboard
Posts: 1971
Joined: Sun Dec 08, 2013 1:40 pm
Location: southern Portugal
Contact:

Re: Grub screws

Post by liveaboard »

Funny;
I was taught it by a Dutchman.
Old cranky machinist had a shop across the canal from my place.
User avatar
Bill Shields
Posts: 10459
Joined: Fri Dec 21, 2007 4:57 am
Location: 39.367, -75.765
Contact:

Re: Grub screws

Post by Bill Shields »

14mm = 9.16" :mrgreen:

We all know what you mean but this falls in with Harold's KG conversion.

Gotta love spell chuckers and inductive keyboards
Too many things going on to bother listing them.
armscor 1
Posts: 311
Joined: Sun Jun 12, 2016 3:12 am
Location: Philippines

Re: Grub screws

Post by armscor 1 »

Commonly referred to as a Dutch Key.
I am from Dutch heritage but have no idea how the name came about.
Rich_Carlstedt
Posts: 1754
Joined: Sat Dec 21, 2002 12:16 am
Location: Green Bay Wisconsin USA
Contact:

Re: Grub screws

Post by Rich_Carlstedt »

it's been called a "Dutchman" in machine shops for well over 100 years .
Maybe it comes from "Plugging the Dike ?

Rich
armscor 1
Posts: 311
Joined: Sun Jun 12, 2016 3:12 am
Location: Philippines

Re: Grub screws

Post by armscor 1 »

80 Amps at 14 VDC is 1120 Watts is about 1.5 HP, substantial load for a set screw or grub screw with a sinosoidal load.
Bob D.
Posts: 381
Joined: Thu Jun 21, 2012 10:43 pm
Location: Saco, ME. USA

Re: Grub screws

Post by Bob D. »

There are keyless style couplings that are a better choice here than the keyed coupling you bought when you have no keyway…..
3/4" Juliet II 0-4-0
3/4" Purinton Mogul "Pogo"
3/4" Hall Class 10 wheeler
3/4" Evans Caribou/Buffalo 2-8-0
3/4" Sweet Violet 0-4-0
3/4" Hunslet 4-6-0
3/4" Kozo A3. Delayed construction project

1 1/2" A5 Camelback 0-4-0
Post Reply