Threading arm with screwdriver

Nice video of the build. I have a feeling that this arm would even manage this screwdriver together with the operator.

I generally like the design, only these linear bearings, as the name suggests are not suitable for the kind of work you are doing. Rotation instead of feed along the shaft. I've used smaller ones and they failed quite easily when forces were applied differently from what the manufacturer intended. They picked up quite a lot of play.

Beautiful construction. And you can see the super "balanced" forces needed to position the "head" in the right place.

rasputnik6502 wrote:

I have a feeling that this arm would even be able to handle this screwdriver together with the operator.

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With his wife and children on his lap. Robust construction.

androot wrote:

Linear bearings, as the name implies, are not suitable for work such as yours. Rotation instead of feed along the shaft.

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And this could turn out to be the cause of any problems in the future.
Although I think that unless the author is "riding" on it with his wife and children, the bearings under the current load will outlive the author.

Elegant design.
In case the unit has to work hard, you can possibly remove the bearings from the housings and insert 30x45 bushings there as pan.
If you don't have time to do the work, you can buy some ready-made ones e.g:

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These linear bearing housings can be cut along the axle and the clearance can be adjusted.
Alternatively, you could replace these linear bearings with four SK 30 or SK 35 linear shaft supports plus some 30x35 pan.
I preferred to choose gravity over magnetism when building my Koromyslo.

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I have two heavy steel blocks with which I can press the Koromyslo against the ground.
This allows me to drill and thread also in non-magnetic sheet metal of unlimited dimensions.
My design is a cross between a drill and a drill press and is just plain ugly.
Here in the layout for fine work.

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But I can always rotate the arm and drill into the 'ground'.
I also didn't use a screwdriver because I like to listen to music.
I can only hear the rustling of the shavings as I work, but I had to buy respectable motors and spindle holders.

Congratulations on making a lovely and sturdy drill and tapping machine.

I don't know what you're getting at with this corom...
To quote my own statement from about a year ago.

I know two meanings of the word and neither has anything to do with drills.

1. koromyslo - a carrier, a wooden device to facilitate the carrying of loads on shoulders, a name borrowed from Ukrainian[1].

Mainly used in rural households, where it is used to carry buckets of water from a river or well. It is shaped like an overlapping, club-shaped beam with a cut-out for the neck. Two containers of approximately the same weight are suspended from hooks at either end of the bar, so that the load of the coromyser remains balanced.

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Source. .

2) Binding someone in a koromyslo - a kind of Soviet torture, it consists in immobilising the person in such a way that one hand is put behind the head (as if we wanted to scratch the neck) and the other is put between the legs, then the torturers bend the condemned person in such a way that it is possible to fasten the hands with stiff shackles behind the back. Then the torturers bend the prisoner in such a way that his hands are shackled behind his back and he is left in the cell to await the next interrogation.

Source - Szczepan Twardoch "Chołod". .

So, please enlighten me as to which part of this machine is koromyslo? I came across this term relatively recently, just in the aforementioned book.
Because maybe I'm just undereducated, but I've searched on Google and all I see everywhere is a bucket-carrying tool.

CMS wrote:

I don't know what you've got with this corom...

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I see a similarity here - the counterweight I used to fully control the pressure of the drill.
You can't see it in the photo, but there is a double-sided lever (double-armed), the weight of the linear bearing, crossbeam and spindle is transferred to the main column.
This works similarly to a coromyser, but mine is unequal-armed.

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If I hadn't balanced the masses of these components I wouldn't have been able to use thin drills.
I would also have a problem with threading.
Balanced is also less perverse.

Years ago I got a "column tapping machine" from a friend, unfortunately it later went to scrap, but in general I remember the construction, the head (something like an ordinary chuck for a column drill) contained one bearing in a strange (I omit the details) simple fixture (two slip rings), hand crank drive, turning clockwise the tapping machine came quickly to the hole, which was to be tapped, then the stroke adjusted itself (there was no automation) to any stroke, then I used various tapping machines, I used a variety of threading machines, the reverse of which caused the tapping machine to go backwards, which it was supposed to thread, then the stroke would adjust itself (there was no automation there) to an arbitrary stroke, I used various threaders, threading, turning in reverse caused the threader to retract, a design to be made by a village blacksmith, at my place, on a really large scale, it worked for five years. I had always planned to make a motor drive but the daily demand for tapping 200-300 holes somehow didn't get me to do it and my older son always earned his ice cream.

I think such devices are still produced as threading heads, as well as for fine drilling.
Maybe I can find cross-section drawings of the construction.
There's a satellite gearbox and something like a clutch, similar in operation to the old bicycle rear hubs.
A higher load reduces rpm while increasing torque. Raising the head up changes the direction of rotation.

For threading blind holes and deep holes I make my apologies with a screwdriver
She 'buzzes' a bit but has an adjustable clutch so I attach her to the Koromysl crossbeam.
I don't have to listen to music incessantly.
I don't look for a spindle with a clutch because I don't do production and for a hobbyist it doesn't really matter.

Congratulations, you are in second place in DIY constructions: https://www.elektroda.pl/rtvforum/ranking.php
And probably immediately in first place.
Respect.
If you allow me, I will send you a small gift. Please specify the parcel number.
Thanks for the presentations!

Forgive the layman's question - what is the measure given at the end of the film?

Frog_Qmak wrote:

Forgive me a layman's question - what is the measure given at the end of the video?

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The white one? That's the coolant.