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A prototyping tool i built.

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Re: A prototyping tool i built.

Postby Mann » Thu Feb 07, 2013 4:22 pm

Oh great another instinctive Vs Gap debate :D :D
Single bevel double bevel, aluminum or carbon or wood 2 blade 3 blade :)
I think we can all agree whether blond or RCH they both get the job done and both are very traditional! :oops: :twisted:

Kirk
Sorry for derailing your thread, Your adjustable riser is pretty cool! :D
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Re: A prototyping tool i built.

Postby Crooked Stic » Thu Feb 07, 2013 6:06 pm

Now days a lot of them dont have any rug at all so size does not matter :arrow:
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Re: A prototyping tool i built.

Postby kcbrown » Fri Feb 08, 2013 5:00 pm

Easy now on them old machinists ;) I have to take issue with the RCH, had one one time that felt as big as a 2 by 4 when it was sitting on the back of my tongue :o Couldnt get that sucker to go either way :mrgreen:
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Re: A prototyping tool i built.

Postby tattman2 » Fri Feb 08, 2013 9:49 pm

Nice jig Kirk 8-) I will post a pic tomorrow of my readouts that are attached to my mill,it is basically built in rulers for reference that can never fluctuate as they are on the ways and probably not expensive to replicate.As for play from left to right on the crank like Mann said could be as simple an adjustment depending on the setup but if you want to upgrade to a tighter tolerance system for maybe using dial indicators on the crank you need to look up ball leadscrews .

here is a site to checkout http://www.thomsonbsa.com/

I have some there stuff on my new cnc and there is NO backlash at all

You could also fabricate a spring loaded leadscrew nut to help with backlash...just a thought :)
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Re: A prototyping tool i built.

Postby Mann » Sat Feb 09, 2013 8:43 am

Just for thought, not wanting or trying to argue. ;)
Ball screws are great on CNC machines. Not generally considered a good idea on manual machines because they have nearly zero friction.
What happens is if you fail to use the table lock and bump or lean on the table it can move a considerable distance. This movement is prevented in a CNC because the screw is coupled to the motor which provides the friction.

Sometimes experience is a real bitch!! :o :?
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Re: A prototyping tool i built.

Postby tattman2 » Sat Feb 09, 2013 9:39 am

It almost seems that anything with friction is going to result in wear :? That is a good point though,I guess there is always a tradeoff.I would think the heft of the ways would be more of a variable than the ball screw assembly for friction. What has been your fix or optimal tradeoff in this situation?No argument here Mann,you know way more about this stuff than me :) Just brain storming
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Re: A prototyping tool i built.

Postby Mann » Sat Feb 09, 2013 11:51 am

True enough that anything with friction will result in wear.
I don't really know how to explain it very well but here goes. If you have a ball screw without the motor hooked up you can easily just push on the table and get motion since the ball nut is set up with balls, any force applied in either direction of travel will only have to overcome the weight of the table to cause it to move.
Where I learned this was we were building a machine with a vertical saw head adjustment and I wanted to impress the customer so we used a ball screw and nut along with a lock.
Well long story short the customer came in for a try out and flipped the lock lever without having a grip on the adjustment crank, and the saw head goes down all by itself. :?
It was only about 3" but he wasn't impressed :lol: , so we replaced the ball screw setup with a lead screw and nut and problem solved.
Not really saying it won't work 8-) just saying it is less headaches to deal with the backlash in the screw and nut than to use the ball screw setup.
Quite a few machine builders are currently offering combination manual and CNC machines that use ball screws. As far as I know all of them are doing the manual motions through the motor with an electrical signal.
While if you buy one of there manual only machines it comes with a lead screw and nut setup.
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Re: A prototyping tool i built.

Postby kcbrown » Sun Feb 10, 2013 7:18 am

All the machines we have at work you select the axis you want to move and use a hand held thumbwheel. You can select how much it moves per rev also. Still it is all done through the motor.
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Re: A prototyping tool i built.

Postby Kirkll » Sun Feb 10, 2013 5:27 pm

Wow this is pretty cool with you guys going back and forth about building these machines. :D .....i'll pass on the rch debate. ether one requires flossing. :shock:

i got a little project I'd like to build for my shooting machine.... You guys up for brain storming something?

I want to build a hook for the string that simulates fingers that mounts on my shooting machine. i'm thinking about 2" wide, slightly radius shape to match the way the string is held by hand as close as possible. i'm not sure whether it would be better to build a plunger that pushes the string off a rounded hook, or actually have the hook hinge like your knuckles do and set up a release of some kind.... Any thoughts on how I'd go about this?

i think it would most likely have to be set up for 3 under. i cant picture how to set it up for split fingers... hell i can wrap my head around setting it up at all actually... :roll:
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Re: A prototyping tool i built.

Postby Crooked Stic » Sun Feb 10, 2013 10:07 pm

You might be getting into some type up robotics trying to get anything close to real fingers.
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