Gallery, Projects and General > How to's
Making a Sub Spindle
sbwhart:
Hi Chaps
Quite a few of you chaps have posted pics of sub-spindles is use either cross drilling, milling or Rose turning, they can be a very useful addition to a shop and have many applications.
I want to build a spindle that I will eventually use as a tool post grinder, as is my way I did a fair bit of investigation work into them, I've seen tool post grinders used when I was tool making and I've also seen John's in use, so I had a fair idea what they look like. I also bought a book from the Workshop Practice Series (No 27 Spindles by Harpit Sandhu ISBN-13:978-1-85486-149-8) and found it very interesting and informative, it covers the design and manufacture of various spindles for different application from milling, drilling, grinding and even a high speed spindle to take dremel tooling.
I will be following the design for a "Light weight tool post grinding spindle" modified for my own use.
This is a sanitized sketch of the spindle.
I've collected most of the bits needed together.
The bearing came from Arc Euro Trade £2 each, Johns started the ball rolling by putting a 20mm hole down the middle of the bar, this was a job that would have made my little lathe grunt (thanks John :thumbup:) this will eventually become the spindle housing. The housing will be bored to fit the bearings, so I'll need the bore clock, and has I'm going to hold the bearing in place with screwed caps I'll need to do internal and external screw cutting, I could have used adhesive to fix the bearing, but where's the challenge in that, so I bought some HSS threading tools from Chronos ( just four days delivery including weekend :thumbup:), I've still to make a undercut boring bar holder, and I'm waiting for the electric motor that I bought on flebay to be delivered.
So I'm more or less ready to make a start in the next day or two.
Cheers
Stew
Majorstrain:
Hi Stew, :wave:
You've got me interested,
It's one tool that I want to make as well.
What were the specs on the motor you ordered on flea bay?
Iv'e been thinking about a brushless DC and controller as used in electric RC aircraft :zap:
Looking forward to seeing the progress reports.
Cheers
Phil
sbwhart:
Hi Phil
Its a sewing machine motor 1/8 hp 6000 rpm you don't need a lot of power for grinding you're only taking a lick off.
I'm planing on having two sets of pulley one set giving 4000 rpm for external grinding and one set giving 16000 rpm for internal, thats what I'm aiming for anyway.
Its not arrived yet bought it over a week ago sent vendor a PM today asking where it is, hope its not a scam.
Cheers
Stew
John Hill:
Stew, this is very interesting!
I have started on a spindle too and I am interested in your comments re the motor size as I have started to build mine around a router motor, not a big router but a lot bigger than a sewing machine motor!
I thought that by using the bigger motor and stepped pulleys I could use it as a drill too (for example drilling holes around a diameter in a flywheel or suchlike).
bogstandard:
To all,
Even though you are normally only taking minute cuts, you do need the grunt there. If you are grinding a fairly large OD, say 3", that is over 9" circumference, it is the constant drag of the wheel that causes the problems. When I grind on my surface grinder say a piece 4" long at 0.0005" (0.01mm) cut, the 1/2 horse motor starts to slow down. So you have a choice, either more grunt to cut thru it, or super fine feeds so there is not as much grinding pressure.
The way to get your very fine feeds is not to use the crosslide for the feed, but the topslide which has been set over a couple of degrees, and the wheel set and dressed square to the job. Grinding angles then becomes a nightmare to set up.
With reference to motors, the original one used on mine (now replaced) was a 1/6th HP free running at 16K.
Bogs
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