Magnetic drills?

[knoba]

I'm after a decent magnetic drill and I think it comes down to one of the two below. Does anyone have any experiences with the dewalt? I've read some good threads on here about the Rotabroach one and know a lot of trusted members use them.

Having never used a mag drill before; do they take side loads well?
Can I get a drill vice (& material) easily underneath them?
Quill depth on the Cobra?

Rotabroach Cobra

• 6 month manufacturer's warranty
• Drill on site or in a workshop
• Cuts holes up to 65mm diameter x 50mm deep
• 1400 watt motor
• Feed capstan may be reversed for easy positioning in tight areas
• Controls mounted at the rear for better access
• 1200 kgs magnetic adhesion
• Variable speed - the right speed for the right diameter
• Automatic cooland bottle
• Supplied with secure carrying case

-*-

DeWalt D21620K

• One year warranty included with this DeWalt D21620K.
• The DeWalt D21620 K is a compact and light weight unit which is both easy to transport and easy to position for drilling.
• Delivers high level of performance for fast, clean and accurate drilling into steel.
• Push button reversible press handle offers tool-free handle set-up.
• The universal quick release cutter holder is quick and easy to operate : no Allen key needed. It accepts any annular cutter with 19mm round shank (Weldon) with one or more flats.
• 3 seconds delayed magnet release avoid drops if the power is cut. The drill will also not restart automatically when powered is restored in order to deliver more safety.
• 2 mechanical speeds for optimized performance.
• Power Input 1150 Watts
• Spindle Thread 1/2" x 20 UNF
• No Load Speed 350/650 rpm
• Cutter holder 19mm Weldon shank (3/4")
• Max cutting depth with cutters 50 mm
• Max cutting diameter with cutters 50 mm
• Drill point pressure 317 Kg
• Clamping force 10000 N
• Length of drill stroke 147 mm
• Weight 13 kg
• Magnetic base dimensions 180 x 84 mm

 

[wyn]

I used to use a rotabroach puma..... it was ok.....no experience of the dewalt.

The only problems i have encountered is on hardened steels such as hardox, when you only have a single speed and really need to slow it down. the only way to do it was to pull harder on the handles to slow the motor.

So i'd have thought a couple of speeds would be handy especially with large dia cutters.

 

[English Steve]

Bit more info here Knoba. Hope this helps.

 

[knoba]

Just; ok ...wyn? That Cobra has variable speed, do you think, in your opinion, it would "make all the difference"? ...build quality, radial play in quil, etc?

Thanks steve, I can't tell you how many times I've read that thread (amongst others). Very informative indeed. What did you decide on in the end? It's a rather specialised bit of kit for an enthusiast (meaning myself). Justifying it is difficult, especially when one considers that, once bought, if it's a really useful tool it often finds a 1001 uses. Add to that, that if it is such a tool, buying a cheap / low spec machine is always, sadly, lamented.

Does anyone use them for purposes other than drilling holes through RSJ's? ...notching?

 

[bucko]

i cant rember what make it was but it was worth it's Wight in gold, the amount of hassel it saved but if your gona drill hardend steel i woul advise geting one with a varilable speed we could not get thew the cutting edge of a backhoe bucket had to brake out the bottles

 

[knoba]

Thanks bucko! ...just the sort of input I was looking for. Good opinions mean more to me than all the facts & figures / sales hype.

Welcome to the forum btw

 

[English Steve]

I went for the Jancy Holemaker 35 in the end, simply because I was able to buy one through work at a good price. I see DIYWelding has the 110V version listed on his website - may be worth a pm for current price on a 240v version (if that's what you need).
Good luck, I know it's a difficult decision.

 

[knoba]

From Dewalts instruction manual:

Pop-off brushes
After 80 hours, the motor will be automatically shut
off indicating that the carbon brushes are nearly worn
out and that the tool needs servicing. The carbon
brushes are not user-serviceable. Take the tool to an
authorised DEWALT repair agent.

80 hours!

Brush life of the Rotabroach?

I've just phoned Rotabroach and they said the "length of drill stroke" is 50mm! I think that they must have mis-understood though as the dewalt looks v. similar with a whopping 147mm drill stroke. Other forum members have reported gearbox trouble on the Rotabroach with 24/7 use. They (Rotabroach) did say, however, that spares are easily available.

This Dewalt has a "bearing bush" in the support spindle housing while the Rotabroach states "needle rollers". ...

Such a pity that manufacturers product info is, invariably, too scant to make a really good informed decision!

 

[Hitch]

The pumas are fairly low cost basic ones, do upto about a 30mm hole.
The cobra is far and away a better buy if you can justify the extra cost.
The gearboxes eventually give out on the pumas if you give it a lot of stick, but easily fixed, parts seem sensibly priced.

Strokes, the puma is quite a small machine, cobra slightly bigger. For broaching though, you dont need much more than that anyway. I would have said the stroke was a bit more than 50mm though from memory, depends on what length cutters you use as to how deep youll be able to drill.

Id steer clear of the dewalt, never used one, but the name hardly inspires any confidence.

Evolution ones are worth a look aswell, sensibly priced and seem to have a decent life.


As for side load, depends what you want to do with it really, but not brilliant.

 

[snowcat]

Rotabroach every time, there priced reasonable and last well, all the talk of rotabroches wearing out has been from everyday use, my own is Fooked to coin a better expression but, Id have no hesitation in buying another when this one finally dies completly.......

Never seen a Black and Decker (sorry dewalt) mag drill, but lots of Rotabroches and evolutions out on site, that might tell you something......

 

[Mikey D]

My Rotabroach ,(puma) is still going strong although its not in daily use by any means ...
dont forget they do the attachment for the baseplates that enable you to drill tube , not seen that feature on other makes , as i said previously my local hire shop use them, that says a lot in my opinion .
That cobra looks the bizz up to 60mm dia

I know which one of the two id go for

cheers mike

 

[knoba]

Cheers chaps, it is, obviously, all settled then.

Three fingers to dewalt. Ha ha haa... i'm free! (happily running through a bright field of fine swarf)