Electronics > Mechanical & Automation Engineering

Boring topic - drilling RPM range etc - affordable bench drill, German market

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TinkeringSteve:
Howdy!

I'm looking for a bench drill for hobby use, a couple weekends of use a year, not a lot of space.
Hence the price/pain point is easily reached ;)
It must operate at 230V single-phase.
Weighing more than I can carry (without inducing back injury), alone, is an excluding criterion - I need to be able to move this around if needed.

I don't need to drill 20mm diameter, 100mm deep, into a stainless steel block.
I don't have much experience with this, was so far only using a hand drill for everything (and not happy with accuracy, esp. angles, of course ;)),
and am looking for a seizable improvement over those kinda results.

(I have seen stand-alone kinda guides with lever, for mounting an existing drill, but my drills don't fit such things and buying this and a new, not too crappy drill, well, might as well...)

Drilling small-ish things mostly, in wood and plastic, perhaps some aluminium and brass - and more rarely, steel of a few mm, if ever.
Things you might do when building musical instruments (e.g. synthesizers in 1970's style, guitar stuff), DIY lab gear, one or the other smaller radio antenna. Probably not anything or much mechanical stuff that moves.
I'm not going to build combustion engines, not even small ones ;)

I've found this supposedly optimal RPM table for different materials at different drill diameters:
(It's Wood, Steel, Stainless steel, Aluminum, Brass, Plastics)
https://www.ellmitron.com/media/4598/file/static/doc/drehzahltabelle-bohren_3366.pdf

I'll get back to that.

I have read about typical German eqivalent "home depot" (Baumarkt) gear as pretty crappy esp. with bad radial runout.
So I found some people who have been reasonably happy with products like the following, supposedly, while made in China, designed in Europe and with decent quality control.
The first one has a guaranteed runout of < 0.03 mm, the other one only claims a reasonably good one, without saying a number - not a good sign I guess.
The things is that the second one has a wider RPM range.
https://www.stuermer-machines.com/brands/optimum/category/product/optimum-drilling-machines/optidrill-dq-18-3191042/
https://www.bernardo-maschinen.com/tb-20-t-bernardo-tischbohrmaschine-230-v.html

What caught my eye was, though, that the 2nd one has a wider RPM range: 180 - 2770 vs. only 600 – 2400 for the 1st one.
Even that already does not cover a lot of materials and diameters from the table linked above.
Esp. plastic with its low RPM requirement (due to heat?)

So I now wonder, how important is using optimal RPM / how much can you deviate without getting horrible results?
The 2nd machine is ~ 100€ more expensive than the other, but the only thing, for met, it seems to have over the 1st is wider RPM range, while the 1st one has a guaranteed runout.
(I also saw an OptiDrill with 0.02 runout, 100€ more, similar small RPM range)

What's most important?

I have heard claims that drills of that kind are of a light construction that might make them bend and reduce accuracy.
The question is - in what scenario? Perhaps not if I drill through a piece of pine or block of plastic?
I don't care about stainless steel.

Please try to not use your own profesisonal or "advanced hobbyist" demands on such a machine as a measuring stick vs. my humble actual needs (probably).
An oft found attitude like "anything below 1000 EUR, used, is crap", is probably not helpful (unless absolutely accurate - but seeing others actually do stuff with those things, I doubt it).
I'd prefer a sober, up to date (to current market) gauging of "what can I do with how much money, and is that enough for what *I* need".
I'd be surprised if I couldn't get a vast improvement over my free-hand drilling on a budget as roughly outlined by the examples given.

But let's hear it ;)

jpanhalt:
Those are probably generic made-in-China goods.
From review of the second offering:

--- Quote ---Für den recht hohen Preis hätte ich mehr als Chinaware erwartet.
--- End quote ---


Initially (1974), I thought speed range might be the most important.  Later, I realized it is not.  It is very easy now to swap that motor for a 3-phase or DC and use a speed controller (assuming the current motor doesn't meet that need).  What is important to me is runout of the spindle and smooth operation, how well does the spindle move,  can you lock the spindle in position, bearings, quality of construction, clamping options, and chuck precision are important.   Both options appear to have table T-slots for clamping.  That is good.

Benta:
I own and use the Bosch PBD 40 and am very satisfied with it.
Don't know if it's within your budget, though. EDIT: followed your links.
https://www.bosch-diy.com/de/de/p/pbd-40-0603b07000-v100026579

2N3055:
Optimum are actually quite decent machines.
But, changing speed by changing belts is a pin in the ass.
OTOH, I agree with Benta, take a look at Bosch PBD 40.

It is not as sturdy ad Optimum you shown, it has aluminum frame. And it is a bit smaller.
Not such a large capacity as that Optimum. But you said you don't need that.
But, it has electronic RPM control, laser pointer etc.
It is very handy, uses little space, and very quick to setup and use. 
They are available at many shops (especially in Germany I would guess), just go to some shop and see it in person.

Optimum would make sense if you wanted more capacity and would like to work with metal more seriously.

Benta:
Concerning drill speed/feed: don't sweat it.
It's not critical in any way for the materials with which you're working. You'll very quickly get a feel for it.
For steel, especially stainless it's a different story.

Your concern about runout: if you intend using normal spiral drills, it's of no consequence at all. Drill flex will be much larger.
Proper punch-marking to give the drill a precise starting point is much more important. Plus drilling in stages.
As an example for a 10 mm hole: punch -> 2 mm -> 6 mm -> 10mm

Normal HSS spiral drills are fine for wood, plastics and aluminium .
For brass you need a separate set, where the cutting edges are ground to zero degrees.

Cheers.

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