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Dreaming of a power draw bar
- Thread starter DPittman
- Start date
To use in the making of a PDB, or instead of?
I haven't seen one that would lend itself to adoptation into a PDB the easy way the butterfly wenches do
The older I get the easier I break! LOL But I've had 2 ankle fractures in the past 6 years that have really affected my thinking. I never thought about safety when I was young and unbreakable.
Good point. Mine is the same.
DPittman
Ultra Member
The bottom end of my spindle does have two flats on it so I guess I could make a spanner for that if it does spin?
DPittman
Ultra Member
Although that's going to require 3 hands...1 for the powerdrawbar operation, 1 for the spindle wrench and 1 to hold the tool/collet in place. Hmnnn I gotta rethink things.
DPittman
Ultra Member
Oh boy I better go to bed, I'm not thinking clearly.
Why would the spindle turn if I can hold it with my hand on it just as well as holding it up top on the pulley?
Good night!
Ya, nothing to grab onto on mine either
My mini-mill came with a locking rod and a hole to lock the spindle from turning.....I think inertia just breaks those PDBs loose and sets them?
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On mine you need to lock the quill fully up or the down force of the power draw bar will push it down and not allow full engagement of the socket onto the top of the drawbar. You can hold the spindle from turning with the same hand that is inserting the collet or tool.
DPittman
Ultra Member
Ok that makes sense. Thank you.
You guys are just like me. I swear I dither about projects for years before I finally get at them and then I wish I did them years earlier. Insert huuuuge sigh here.....
No way. A guy my size would collapse that thing and I'd knock over my BPort. Thankfully, I don't need one. If I did, I'd make a big one out of wood with outset legs so it would never flip on me. The only thing stools get used for in my shop is temporary workbenches to put tools and parts on.
Related question for you drawbar focussed guys:
Assuming that we are talking R8, how tight is tight enough?
I would think that its a function of the size/area of the tool engagement. A 3/4" tool needs more torque than a 1/4" tool. But maybe there is a standard that works for all.
I sometimes worry I'm too tight. I've seen what insufficient torque does.
I asked this same question in another thread but nobody volunteered an answer. It probably got overlooked or its a dumb question and I'm too dumb to know it.....
Assuming that we are talking R8, how tight is tight enough?
I would think that its a function of the size/area of the tool engagement. A 3/4" tool needs more torque than a 1/4" tool. But maybe there is a standard that works for all.
I sometimes worry I'm too tight. I've seen what insufficient torque does.
I asked this same question in another thread but nobody volunteered an answer. It probably got overlooked or its a dumb question and I'm too dumb to know it.....
I wished for a PDB for years - reaching up there for manual tooling changes just wore me down. Finally built a simple one using a Princess Auto Butterfly wrench. It was a great improvement - with one caveat : watch your air pressure and think twice before making any heavy cuts. In the last 6 months since I built mine, I've had 2 incidents where an endmill pulled itself down in the collet. My air compressor is a bit on the noisy side and I don't always turn it on. If your air pressure has "sagged a bit" and you step into a heavier cut, you may be at risk of an end mill slipping down. I saw a comment a few days ago saying that PA has a heavy duty butterfly - I probably got the weaker one. Gonna turn my air pressure regulator up a bit when I go out there today.
DPittman
Ultra Member
You know what they say about dumb questions...no such thing as a dumb question only dumb answers. I too have been wondering about the correct amount of torque on the drawbar.
I have found out the hard way what too little torque does but I really don't have a clue what enough or too much really is. The cheap butterfly impact wrench I bought has maximum torque of 75lbs. I relate that to how much torque I put into tightening wheel lug nuts on my minivan, (recommended about 75-80lbs. I would think that sort of torque on my draw bar would be certainly adequate but not excessive. I considered the higher end impact wrench that delivered 180 lbs but was worried it would be too easy to over torque the drawbar with that. Now I don't know if the cheap impact wrench will actually deliver that sort of torque easily and consistently or only with oiled threads, 120 psi and on a sunny day. I guess I should test that.
???
I have found out the hard way what too little torque does but I really don't have a clue what enough or too much really is. The cheap butterfly impact wrench I bought has maximum torque of 75lbs. I relate that to how much torque I put into tightening wheel lug nuts on my minivan, (recommended about 75-80lbs. I would think that sort of torque on my draw bar would be certainly adequate but not excessive. I considered the higher end impact wrench that delivered 180 lbs but was worried it would be too easy to over torque the drawbar with that. Now I don't know if the cheap impact wrench will actually deliver that sort of torque easily and consistently or only with oiled threads, 120 psi and on a sunny day. I guess I should test that.
???
I referred to this article in my thread on the CNC conversion.
Posting with link to Rick Sparber's WUT
I find that for normal wrench based draw bar work that I don't need a spindle lock.
The impact wrench when just used by hand on my mill without using the second wrench for the WUT doesn't really turn the spindle. But now that I have an AC servo I'm finding it acts as a brake and prevents the spindle from turning.
However, depending on how your upper drive section is configured, if you use pneumatics to bring the impact wrench down then as it goes down it could push a spring loaded pin that would drop into a hole in the pulley if the spindle did make one turn. Or put in 3 or 4 holes to keep things balanced.
Doesn't even have to be pneumatics. If you have a lever you pull down to engage the socket that then closes a switch to enable an electric impact wrench you could have that also push a pin into the pulley. That leaves one and on the lever, perhaps even twisted clockwise or counter clockwise to load or unload the draw bar. The other hand to hold onto the tool or catch it.
Posting with link to Rick Sparber's WUT
I find that for normal wrench based draw bar work that I don't need a spindle lock.
The impact wrench when just used by hand on my mill without using the second wrench for the WUT doesn't really turn the spindle. But now that I have an AC servo I'm finding it acts as a brake and prevents the spindle from turning.
However, depending on how your upper drive section is configured, if you use pneumatics to bring the impact wrench down then as it goes down it could push a spring loaded pin that would drop into a hole in the pulley if the spindle did make one turn. Or put in 3 or 4 holes to keep things balanced.
Doesn't even have to be pneumatics. If you have a lever you pull down to engage the socket that then closes a switch to enable an electric impact wrench you could have that also push a pin into the pulley. That leaves one and on the lever, perhaps even twisted clockwise or counter clockwise to load or unload the draw bar. The other hand to hold onto the tool or catch it.