Author Topic: Quick-step  (Read 4725 times)

Offline Bjorn

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Quick-step
« on: October 26, 2015, 05:49:12 AM »
No, I'm not refering to the shuffling of feet to and from at the dance hall, but rather the milling attachment designed by John Payne. This has in the past been avaliable from hemmingway in bouh a kit form and as a complete machine as I understand it. At quite a cost to be fair..

However, I have dug out the issues of mew where it was serialised as a construction article and I am now thinking of building one. Currendly I am at the stage of proofing the drawings in cad (allways a worthwile process) and I have allso sourced a piece of aluminium rectangular box tubing allbeit in metric dimensions for the gearbox housing (could not find 2 1/4 x 3 3/4 x 3/16 anywhere.

Any input on this is most welcome

Offline PekkaNF

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Re: Quick-step
« Reply #1 on: October 26, 2015, 07:02:58 AM »
Intresting.

What do you think of gears and DC-motor?

That small motor and wide diameter of drills/mills and materials needs consideration on rpm.

I have been toying with same basic concept but with poly-v, AC-motor and VFD. It turned out a bit heavy. 0,18 kW 3000 rpm motor is about 3,2 - 4 kg. Also tried a little 200w AC servo (half the size and quarter of the weight), but it needs a servodrive, it is not stable enough with my VFD.

Skip few years....now there are DC BLD motors and drives. I bough one 48V and 200W or something. I haven't bolted it on anything, just tried it out of the box and it definately has something on it. Some years ago I calculated typical mill/drill speeds for steel and AL for 3-6 mm diameter. And concluded that hight end close to 2000-4000 is desirable, but not that critical really.

Where problem lies is torque at the 5/6 mm drill and mills, have to gear down to 400 to 600 rpm while motor produces top power (i.e. close to nominal rpm). This is where normal AC motor excels, 4kg 0,18kW motor can be abused short time twice the torque at nominal rpm and only problem with quality motor is that it might inflict burn on your arm, whereas other motors cut out or start smelling funny.

Original step mill is a self contained unit, all controls on it. Any modern motor needs a separate unit for power/controller, depends on personal preference. I like it, but I see if anyone has different arguments. I like low voltage and well insulated stuff.

Not sure if this personal rambling is of any use, but use what you like, and critisize rest of it.

Pekka




Offline Bjorn

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Re: Quick-step
« Reply #2 on: October 26, 2015, 07:20:53 AM »
Hello Pekka!

Yes, the motor concept is a bit outdated on the quickstep as it is. I will propably go for some kind of dc motor up to 24V as I have a variable lab supply (0-24V max 900W) in the workshop. It is mostly used to feed a lipo charger.

I will propably keep the gearing and pulleys as they are because of the tourqe advantage combined with a high top speed (toolpost grinding)

Mind you, the original QSM weighs in at about 4,1 kg according to the articles...

RobWilson

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Re: Quick-step
« Reply #3 on: October 28, 2015, 11:53:15 AM »
Hi Bjorn


I have the  Quickstep attachment on my build/tool list  :thumbup:  ,I can see it being a handy bit of kit to have in the shop .



Rob

Offline Bjorn

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Re: Quick-step
« Reply #4 on: October 29, 2015, 10:53:26 AM »
Aluminium box section for the gearcase arrived from germany today! it's a bit higher at 100x60mm in dimension then the original design, maybe I will cut it down and put a lid on top instead.

The gears will be metrificated as gear cuttters in DP 32 are quite rare and will find little use after this. Will keep the same gear ratios with Mod 1,0 and Mod 0,8 gears instead (20/60 32/32 and 16/48). Centre distance between shafts ends up at the even number of 32 mm instead of 31,75.

Ordered a set of ER 20 collets and gear cutters today.

Hm.. Maybe I should have built that Eureka backing of device..

Offline awemawson

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Re: Quick-step
« Reply #5 on: October 29, 2015, 01:23:40 PM »
...ah but .... 31.75 mm IS a nice round number in Imperial measurements 31.75 / 25.4 = 1.25"  :lol:
Andrew Mawson
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Offline Bjorn

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Re: Quick-step
« Reply #6 on: October 29, 2015, 01:48:57 PM »
In imperial, yes. Will not start a debate over this, it is still just a number on the dro... Have made a fair bit of parts to imperial measures so I have no issues with it, I convert all measurment to mm anyway before machining.

Offline Bjorn

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Re: Quick-step
« Reply #7 on: November 24, 2015, 01:28:28 PM »
Not much have happened so far, getting married got in the way somehow..  :thumbup:

Been busy tidying up the drawings from the old MEW Magazines in turbocad, it is allmost done now.

Gearcutters (Mod 0,8 and Mod 1,0) , ER-collets and other bits and pieces are slowly accumulating so I should be get started soon.