Thread: Budget Power Drawbar
Hi guys, just a small look at a power drawbar myself and a friend knocked up at the weekend. After using a (home built) manual drawbar release for a few months, I decided I needed something that worked with a flick of a switch. I didn`t want to go down the "air operated" route because quite frankly I just hate it when a compressor fires up unanounced! So this is what we came up with.
The motor, I got from another friend, (which originally came out of his mothers threadbare recliner chair), the frame is an old fireplace lintel (from back in the day when everyone had a brick/stone fireplace in their living room) which I cut and welded to suit, the base is an offcut from a plastic fence post and the switch I had lying around. Total cost for the whole lot ----------- zero.
I have been trying it out over the past two or three days, and it has been faultless ! I never expected it to work as well as it does, it takes just less than two seconds to release the tool, and the same to pull it back in. And the huge bonus is ---- it`s silent.
This power drawbar has been fitted to my RF45 mill, which again myself and my friend converted to cnc about a year ago. Anyone thinking about a power drawbar may want to look into using one of these motors, as the power they have is unreal !! my friend actually took away the other motor to make himself a power broaching press.
Anyway, hopefully these pics will show up, apologies for the black border in a couple of the pics, I had to do that to prevent them from being rotated.
These were just after we tacked the frame together, to give it a few trial runs.
And now a few more after final welding and a coat of good old hammerite.
Last edited by needleworks; 09-12-2015 at 10:46 PM.
WOW!!!.. very impressed. I love the ingenuity of it.
Any likelihood of a cheeky video?
I love to see inventive repurposing - makes me well up inside
Would have loved to have seen this when I was faffing about with my Chester Lux.
Is it on the MT4 or R8 spindle?
So start making an auto tool changer then and show us!
I did think about it, a couple of years back I built a geneva mechanism for another mill that I had cnc`d, which was gonna have a tool changer! Unfortunately I sold the mill before I got the chance to do the atc.
I`ve still got the mechanism lying around somewhere
How does the clamping of the tool work. Or do you have only a collet for clamping cylindrical tools with the same diametre?
The collets clamp on a 3/4" diameter cylinder but it also allows the toolholder to have contact with the spindle nose. This makes tool length offset through the tool table possible as you can premeasure the length of each tool and it is repeatable. I find them worth every bloody penny when you have to change tools for a specific job as it saves having to touch off each one. In conjunction with the power drawbar you literally fly through.
The holders look like this one:
Tormach in the US claim to have invented this but there are a number of sources out there that manufature them.
Needleworks probably has a set or ER20 chucks but you can get ER16 up to ER32.
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