DIY OD Grinder fixture, For the surface grinder- maybe

[Janderso]

Hill Top machine has two videos out on his idea for this handy gadget.
Tin Barn Time also made one.

Using a cheap spin indexer and a small motor is the starting point.
This motor is a 220v gear motor. It has a high speed of around 360 RPM. It's high torque so I should be able to seed it up without any problem.
I don't like the idea of using the spin indexer as is without coming up with simple bronze or ball bearings. Of course an oring would be needed to keep out the swarf on both ends.
A 5C platform is a great way to start.

I'll be watching Hilltop Machine and meanwhile, I'll get working on this.
I need to make a base that will hold the indexer and motor off the magnet far enough to give me some work area for at least 5-6" of stock.
See pic.
A long way to go

 

[mmcmdl]

Hey ! That's one of OUR guys isn't it ? Like right down I 81 ?

 

[jwmelvin]

I thought OD grinding should spin a part with a reference surface against the OD (not a bearing-defined center), so calling this an OD grinder isn’t right. Robin Renzetti did an OD grinding fixture.

This punch/cylindrical grinder is a good idea though. I am also interested in making one, after spinning by had a few times. I don’t see why you’d want such a high rpm though, by an order of magnitude.

 

[jwmelvin]

Do these spindexers not have bearings? My unihead, which I’ve been using for cylindrical grinding, definitely does. I guess I need to disassemble one of my spindexers.

 

[woodchucker]

I have used my spindexer without a motor, hand cranking. I don't use it enough to worry about a bearing surface. It's cast iron, I use the lock hole to keep squirting oil in, and the spindle already had a layer of oil before I start..
if you are going to use it often, I would think you need to cut a channel for oil .

 

[Janderso]

I thought OD grinding should spin a part with a reference surface against the OD (not a bearing-defined center), so calling this an OD grinder isn’t right. Robin Renzetti did an OD grinding fixture.

This punch/cylindrical grinder is a good idea though. I am also interested in making one, after spinning by had a few times. I don’t see why you’d want such a high rpm though, by an order of magnitude.

You are correct, this would be my version of an OD grinding fixture.
Lots to be considered and corrected. The datum of the spin indexer has to be co-planer or parallel with the table, the base has to be ground for easy set up to get it 90 degrees to the wheel, etc..

 

[Janderso]

Do these spindexers not have bearings? My unihead, which I’ve been using for cylindrical grinding, definitely does. I guess I need to disassemble one of my spindexers.

No bearings in these jippo models. Just a slip fit. The tube is pretty hard, the indexer ID is just cast iron.

 

[woodchucker]

Jeff, most grades of cast iron have enough graphite to be a lubricant. My lathe has a cast iron bearing.
Your quill goes up and down in a cast iron bearing.
The only thing lacking is a lubrication channel.

 

[mmcmdl]

My spindexer traveled south . I can't remember if it had bearings or not , but I don't think they do .

 

[Janderso]

Jeff, most grades of cast iron have enough graphite to be a lubricant. My lathe has a cast iron bearing.
Your quill goes up and down in a cast iron bearing.
The only thing lacking is a lubrication channel.

Good point about the cast iron bearings. In this case the bore needs to be tightened up. I haven't measured yet but there is too much play between the tube and the bore.
I'm thinking oring grooves and bronze inserts. I can machine the bore enough to fabricate some bushes. What, maybe .001" clearance?? Have to use way oil so there has to be some room there.