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What machine for grinding tiny precision threads?

Conrad Hoffman

Diamond
Joined
May 10, 2009
Location
Canandaigua, NY, USA
This probably doesn't exist, but what machine might be suited for grinding tiny fine pitch (1-4 mm diameter) leadscrews about an inch or two long? Material would be hardened stainless.
 
This probably doesn't exist, but what machine might be suited for grinding tiny fine pitch (1-4 mm diameter) leadscrews about an inch or two long? Material would be hardened stainless.

To heck with ground threads, you need miniature ballscrews - available to 1.8mm shaft diameter: KSS JAPAN | Ball Screw & Actuators

What accuracy is needed? How many? You can check with these guys to see if they'll make what you need: Helix Linear Launches New 1.5, 2, 3 and 4mm diameter Miniature Lead Screws
 
Thanks for the Helix link- that might be the answer. We can't use a ball screw because our product design relies on friction. Accuracy isn't important in the traditional leadscrew sense; it simply has to have a low pitch error in relation to a short nut, which would always be the case with a competently made screw.
 
Matrex made a model 33 which would grind 12.5 mm x 102 excell made a machine about the same size. You're looking for a machine that there weren't very many made so you might have to go overseas to find something.
 
I would say a thread grinder is the machine to grind precision threads on cylindrical parts. We used to have one of them in our shop to grind threaded mold inserts and plug gages.
 
I'm trying to think of why a lathe fitted with a tool post grinder is not "as good as it gets".

Coolant and shielding from wear promoting grinding debris a given.

I can see automated wheel dressing a boon, but that is not rocket science.
 
Drake looks interesting. As for tool post grinders and such, there's no way to control the size with sufficient accuracy on something as crude as a manual lathe. I don't know if anybody puts such on CNC machines, but you need micron resolution for these small threads. You also have to adapt for the helix angle using a wedge or something. At the size in question, support is a huge issue. I've cut them successfully in softer materials, but need to grind much harder materials now. I'm also thinking a tap and tool grinder like a Rollomatic might be ideal, but the cost is out of sight. Not something you'd find in a job shop either. Question- do people put live tooling like grinding wheels on Swiss machines? That would seem to solve a lot of the support issues.
 
How many of these are you looking to grind. You would have to do an awful lot to justify a CNC thread grinder or even a used one for that matter.
 
Drake looks interesting. As for tool post grinders and such, there's no way to control the size with sufficient accuracy on something as crude as a manual lathe. I don't know if anybody puts such on CNC machines, but you need micron resolution for these small threads. You also have to adapt for the helix angle using a wedge or something. At the size in question, support is a huge issue. I've cut them successfully in softer materials, but need to grind much harder materials now. I'm also thinking a tap and tool grinder like a Rollomatic might be ideal, but the cost is out of sight. Not something you'd find in a job shop either. Question- do people put live tooling like grinding wheels on Swiss machines? That would seem to solve a lot of the support issues.

Any translation mechanism is capable of "micron resolution" when fitted with suitable measurement devices.

"Impossible" is often the easiest thing to overcome.

Or, you could just do what is so often suggested here on this forum. Send the work out to someone who is already doing the operation with the "correct equipment.

Then save your coin and purchase the tool that is correct for the task based on the success of the outside shop. Of course, then you will need to come up to speed on all the details and nuances of operation.
 
I've fluted under a mm .027" to be exact on a cnc rollomatic with various diff helical pitches from 12 degrees to 26 degrees. With the correct set-up its flawless everytime. Depending on flute length they run at most 3 mins a part and if you have a large quantity needed, they can be auto loaded by the robot up to 600 pieces max!!! Very reliable and holds up to a .001" very well!!
 








 
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