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Help needed; Finding plans / Ideas for a homemade drillpress.
DavidA:
If you are making the drill press from scratch it would be very usefull to design it in such a way that the head can be swung off to one side and returned to exactly the same position. This will allow for changing drills and taps etc without having to use lots of quill extention.
Dave.
Lew_Merrick_PE:
--- Quote from: NeoTech on January 27, 2013, 04:09:05 PM ---hmm well.. I usually need to drill the small pilot holes before i bore something larger..
smallest, 2mm.. biggest, hmm about 25mm.. im thinking of doing a "swing" table on a sleeve and a rack and pinion to be able to rise and lower the table. Ive found this old 3kW electric motor, that is 3 phase lying around in the garage from some other project so im thinking belt drive and a three speed controller for the motor..
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3 kW is a lot of power for a drill press. Most commercial units covering that range would have a motor between (about) .38 and .57 kW. Too much power will make drilling with small (say < ø1 mm) bits more difficult (they break with too much torque).
The swing I was referring to is the distance between the centerline of the chuck and the edge of the column. This measure is usually rated as the largest diameter of (round) part to which you can drill to its center. Being able to reach 200 mm from the column to the center of what you are drilling is (generally) called a 400 mm swing.
I would actually recommend using a cable drive system with pulleys and a counterweight for raising and lowering the table. (1) It is simpler to build and (2) it is (usually) easier to operate.
--- Quote from: NeoTech on January 27, 2013, 04:09:05 PM ---i have a hard time to wrap my head around that "spline drive" thingy. I cant really in my head see how it should be able to spin and move up and down at the same time..
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In commercial practice, a spline-shaft is essentially a long spurgear. The driving side is a spline-drive that is essentially a round OD part with a mating gear-shaped hole broached in it. The drive-belt turns the spline-drive which, in turn, spins the spline-shaft -- which can move (axially) up & down with respect to the spline-drive. Whatever the Norwegian equivalent of Machinery's Handbook will have information on these types of parts.
Now it is true that a spurgear type of interface is going to be the most efficient of this type of drive interface. However, a reasonable equivalent can be made by using a square or a hex shape. These are much easier for the home-shop type of equipment (and, usually, skills) to make. The closer you come to a true circular interface, the less shaking will be induced by the eccentricity of mass. A square shape interface will drive more power, but it will shake (induce more vibration) into the drive than a hex shape interface. An octagon shape interface will drive less power than a hex shape interface, but it will vibrate less. (Etc.) Another alternative approach is to run long keyways on the shaft that can be driven by keyseat broached or cut (i.e. filed) into the drive hub.
I would (generally) recommend a hexagon drive interface.
--- Quote from: NeoTech on January 27, 2013, 04:09:05 PM ---Anyway, fixed head and moveable drill table i think its the best way to go about this. I need about 100mm of travel for the drill but the table need to be lowered for larger stuff.
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If your I think about it and XXX throw is about right number is 100 mm, then I would design for 150 mm of throw as that should not add too much trouble or expense and will save your bacon when you discover you need that extra 10 mm! More is almost always better in this regard!
PekkaNF:
That big drilling range suggests two different size drill press. It's pretty easy going until 12 mm, then you really need heavier machine. Punching 12 mm drill into normal structural steel with tabe speeds and feeds needs about 200 kg equivalent force to push, if I remember right. Also speed/torque range is quite different.
How would agricultural cardan shaft spline work? Least here you can buy shaft/sleeve by meter.
Like this (page 7 different types of splined shafts and tubes. They would transmit the power you need and they are pretty cheap.
http://www.vapormatic.com/_assets/documents/pto%20catalogue.pdf
Then again for a smaller drill, aforementioned hex extension bar, like this:
http://www.mad4tools.com/spectrum-hex-extension-bar-250mm--allen-key-jx25-for-dry-core-drilling-5183-p.asp
Would donote parts.
It all depends...I see pilar drills with MT3 weight only 200kg and wonder how do they fare.
Then there is this one. MT1 tapper and about 1000 kg and not too much cast iron. See Hauser 2A2:
http://www.lathes.co.uk/hauser/
What kind form factor and size of construction you have in your mind?
Pekka
philf:
My drill is a massive Fobco Seven-Eight and it's theoretical capacity is 7/8" (which is the biggest drill normally supplied with a 2MT shank). It will drill 1" as I have tried it with a drill with a reduced taper but the torque requirement necessitates engagement of back gear. I don't know what you had in mind for speed changing but I don't think you'd get enough torque/speed reduction with e.g. a single v-belt. A wide, heavy duty POLY-V arrangement might work but a back gear would be better.
I'm only using a 3/4 HP motor but driven from an inverter which can't output 3/4 HP. I have never stalled it. 3KW (4 HP) is way too big.
I would endorse going for 150mm stroke rather than 100mm.
Splined shafts and bushes are available off the shelf but aren't cheap: http://www.ondrives.com/data/pdf/linear/linear.pdf (See pages 188 onwards.)
I don't like to be negative and I'd be interested in seeing what you manage to build but I can't help but think that you'd be better buying a second hand machine.
Good Luck.
Phil.
Meldonmech:
I use drills from 1/8 up to 5/8 inch in a bench drill, this has a no 2 morse taper quill, a 1/2 hp motor, and 12 speeds. Larger drills up to 1 1/2 inch I use in the 626 Mill, this has a no 3 MT and a 1 1/2 hp motor, lowest speed 120 rpm . Slow speeds are essential when drilling cast iron with big drills. There is also the mass of the machine to consider, larger drills generate high torques and vibrations, which require dampening and absorbing. A heavy preferably cast iron structure is required to satisfy these requirements.
Before you become too involved with the build take a visit to a machine tool supplier, ask questions about
machines they would recommend to satisfy your requirements, take brochures and specs. Carefully analyse the data, then you will be in a much better position to begin your design.
Good Luck David
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