Magnetic Drill for Woodworking

[Aaron Inami]

Okay, I'm re-posting this last message to start a properly "named" thread for other's interesting.



So I rented the Milwaukee from a local Sunbelt. Unfortunately, this is not so good of an experience. The bad part was the drill had such extreme run-out on the chuck that it was unusable. I made a short video here so that I have documented results when I ask for my rental money back:

https://www.youtube.com/shorts/5ylJp48sRIM

I'm using a long bit just so that Sunbelt can see, but I measured a runout of 10 thou right at the chuck. In addition, the slide had a lot of play which allowed the drill bit to wiggle and drill at an angle. The unit was so beat up. I'm sure that many people dropped this on concrete and into the back of trucks and such. The weight of the motor caused the slide to drop down all the time (putting pressure on the bit) which made it very difficult to mount bits properly.

I'm glad I rented it though because it really showed that this unit is just too large to be practical on material (surface area required for metal plate and base plus motor). That being said, I measured a distance of 5" from the chuck center-point to the base, so you could mount up to a 10" hole saw if you really wanted to. It is heavy, but lifting it up onto a work surface is doable. However, because the motor constantly dropped down, I had to hold the feed handle at the same time a trying to lift the unit so that the bit/motor wouldn't drop down. Ugh.

I have a local place that has a small magnetic drill that I will try next (although it's a single speed).

I did do a drill test and this unit has excellent power. The couple of Forstner bits I had went though the wood like butter at mid RPM (probably 200 rpm), but this Milwaukee is just too physically large. lol.

[Aaron Inami]

This weekend's effort was renting a smaller magnetic drill from a local place. They had a Baileigh MD-3500. It's a single-speed motor that is geared for 595 RPM at the bit. It was in significantly better shape and the drill was super tight and accurate (no runout at all). I will say that this unit is really damn loud (so loud you have to use hearing protection -- like a screaming Dewalt 735 planer! lol). It would have been nice to have a variable speed and a somewhat quieter motor, but this will get the job done this weekend. The larger Milwaukee 4206-1 magnetic drill had a nicer motor, but the unit was just too physically large to work with. I may look into getting a variable speed setup sometime in the future. The following demo video shows a drill test in some scrap plywood. I was going slow in the video, but I'm sure I could push the bit through faster. I need to drill precision Forstner hole in the middle of a sheet - something that a drill press won't do.

https://www.youtube.com/watch?v=9_d9z0E-jOM

It's a good alternative and useful tool.

[Edward Weber]

Forgive me if this seems harsh but why are you looking at these tools for woodworking?
There are tools better suited for the task.
There are plenty of portable drill guides available or a radial drill press.

[Aaron Inami]

See the following thread. I have already gone through the "drill guide" options with poor results (see where I picked up in the following thread). I need precision hole in the middle of a large sheet. A radial drill press will only have about a 16" reach into the material. This is not enough.

https://sawmillcreek.org/showthread.php?278558-Portable-drill-press-for-hand-drills/page2

[Tom M King]

Was that the model with the MT3 head and the chuck is mounted on a MT3 taper? Mine is, and the taper has to be clean or it multiplies by the time it gets down to the chuck jaws. The chuck can be taken out by hand with a big knurled surround on the part that screws to the drill motor.

Mine, that I bought off ebay had runout too, but after cleaning it out good, it did great.

That rental one could very easily have been dropped too. People don't generally take care of rental equipment.

Yes, it's a beast to have to move around. In any case, I'm glad you rented one before buying one. I don't remember having trouble with the motor dropping while moving it, but it's been a while since I used it. Something doesn't sound right about that either. Probably just a typical piece of rental equipment.

[Aaron Inami]

The Milwaukee I rented from Sunbelt was not the MT3 version. It was the model with the 3/4" chuck built into the motor. The slide was really loose with a lot of wiggle (wouldn't hold the bit straight). I'm sure all of these problems were from being dropped on concrete or thrown into truck beds by contractors who don't care that they are abusing a rental tool. lol. I have watched multiple videos on the Milwaukee and none of them presented the problems I experienced with the Sunbelt rental.

[Edward Weber]

See the following thread. I have already gone through the "drill guide" options with poor results (see where I picked up in the following thread). I need precision hole in the middle of a large sheet. A radial drill press will only have about a 16" reach into the material. This is not enough.

https://sawmillcreek.org/showthread.php?278558-Portable-drill-press-for-hand-drills/page2

How precision a hole?
What size hole?
How far into the center, 24"?

Could you use a plunge router?

[Dave VanDewerker]

Maybe I am missing something here, but why not use a scrap piece of plywood with the the correct size hole you want drilled thru it and double stick tape it to the sheet and use a router with a pattern bit to cut the hole.

[Phillip Mitchell]

Maybe I am missing something here, but why not use a scrap piece of plywood with the the correct size hole you want drilled thru it and double stick tape it to the sheet and use a router with a pattern bit to cut the hole.

I agree. Maybe I don’t understand the context well enough, but I had a similar task to do recently and did what you have outlined above. Considered plunge router with guide bushing, etc etc but a double thickness (1.5”) plywood template properly laid out with attention to drilling depth was all that was needed for perfect enough accuracy in a pretty high end application.


What is the context of this drilling?

[Aaron Inami]

Maybe I am missing something here, but why not use a scrap piece of plywood with the the correct size hole you want drilled thru it and double stick tape it to the sheet and use a router with a pattern bit to cut the hole.

I have actually already tried that. First, it's really difficult to find a router bit that is long enough to reach 2-1/4" down. Second, the two router bits that I tried were not 100% accurate. One router bit under-cut the hole by 0.3mm and the other router bit over-cut the hole by about 0.25mm.

[Ken Fitzgerald]

I have actually already tried that. First, it's really difficult to find a router bit that is long enough to reach 2-1/4" down. Second, the two router bits that I tried were not 100% accurate. One router bit under-cut the hole by 0.3mm and the other router bit over-cut the hole by about 0.25mm.

Really? You consider when working with wood, a dynamic material, 0.3mm or 0.25mm an inaccuracy? The only time I have ever dealt with that type of accuracy was centering the x-ray tube on CT scanners in all 3 planes after installing a new tube. Then we used special jigs, phantoms and software to measure those type of extremely small specifications.

People routinely route thick materials using a combination of two different router bits.

[Kent A Bathurst]

........ 0.3mm or 0.25mm an inaccuracy?...

Ruh-roh. I gotta scrap the three end tables in process and start over.

[Dan Friedrichs]

I have actually already tried that. First, it's really difficult to find a router bit that is long enough to reach 2-1/4" down. Second, the two router bits that I tried were not 100% accurate. One router bit under-cut the hole by 0.3mm and the other router bit over-cut the hole by about 0.25mm.

It's not hard at all to find long router bits. Easy to buy even a 6" long bit.

If the hole is "under-cut" (you mean in diameter?), then isn't it just your template that needs adjusting?

You're talking about <1/64" error. How are you handling even positioning this drill/jig/router/whatever with better tolerance than this?

[Phillip Mitchell]

It would be helpful to know what the details of the application are to enable a bit more of a specifically targeted response…as opposed to all of us saying “you’re worried about 0.3 mm?”

I have seen extra long spiral and straight 1/2” shank router bits from Amana / Tools Today in the past, though without knowing more details, it would be hard to recommend much more specifically than that.

[Richard Coers]

You don't have to reach all the way through wood with a single straight bit. You can bore down with say a 1 1/2" long bit. Then drill a 5/8 hole through to the other side. Then switch to a flush trim with the bearing on the bottom and come from the other side of the board. Run the bearing on the previously routed hole. But with you need for high precision, you may want to look into a jig boring machine.

[Edward Weber]

IMO, I think you need to pump the brakes and rethink what you're after.
You want to bore some a 2+" deep hole into some sheet goods, far from the edge.
A router and properly sized template is what most of us would use.
You seem to be trying to attain extremely tight tolerances, can we ask why?

2 1/2" bit shown, Amazon, easy
501959
If you're concerned about .25mm (.009") variance, you're using the wrong material. Insert a metal bushing to achieve those tolerances.

We're only trying to help but more info is needed.

[Aaron Inami]

For people following this discussion, I fully documented my project in the following thread, which also contains a demo video:

https://sawmillcreek.org/showthread.php?303972-Felder-FAT300S-table-as-a-work-bench

[John Downey]

Dam dude! 10 mil runout at the end of a crazy long spade bit is nothing to complain about! You just add errors measuring runout anywhere but at the taper.

I've seen mag drills that really were dropped on the chuck, that's your setup, not a flaw in the drill.

(as an aside, I even remembered the password I haven't used in 10+ years :D )

[Aaron Inami]

If you read my post carefully, the 10 mil runout was right at the chuck itself. The runout at the end of the crazy long spade bit was something like 1/8". The mag drill was obviously dropped on concrete multiple times by renters who didn't care. My second mag drill rental went perfectly.

[John Downey]

If you read my post carefully, the 10 mil runout was right at the chuck itself. The runout at the end of the crazy long spade bit was something like 1/8". The mag drill was obviously dropped on concrete multiple times by renters who didn't care. My second mag drill rental went perfectly.

Fair enough - I'm definitely guilty of not reading closely.

10 mil at the chuck is bad, but not as bad as I've seen from repeated drops. In most cases a mag drill is not considered a precision instrument so I would say that is at the outer limit of acceptable, and not surprising from a rental tool. You got lucky with the desk guy if they gave you a refund.

The other thing to watch for with mag drills is a weak magnet. People don't seem to know that they are designed to be used on a minimum thickness steel (varies by size and manufacturer, but say around 3/8" plate). Thinner than that and the bit pressure can lift the magnet off if you have some white knuckle rental gitter dun type users. Eventually the magnet weakens from over heating - over heating thins the shellac on the windings and current can leak across. At least that was what I came up with to make sense of it - the reasoning could be an utter big story, but the effect is still something I've seen with mag drills that were rode hard and put away wet.

[Tom M King]

It was great for this kind of job. Sensitive steering linkage under three layers of 1/4" steel the 3/4" bit had to go through. This one has not been abused. 5,500 lb. test marine lifting ring installed.

[Keith Outten]

Tom,

That's a healthy mag drill.
Glad I don't have to lift it :)

[Tom M King]

Makes changing blades easier and safer.

[Keith Outten]

Nothing like having your own tractor :)
I have the large Baileigh mag drill but have not used it yet, not sure how I can handle the weight these days. Inside my shop I have an overhead winch that I use to lift my lawn mower up to sharpen blades like you do and a whole host of other tasks.

I just ordered a pallet fork attachment that will be used as a lifting boom so I can move stuff in and out of the second floor shop office window.
I just can't haul heavy or bulky stuff up and down the stairs anymore. I hope that it will also help me load 12 foot long solid surface sheets into my shop panel saw from the roll up door. I don't have a helper anymore so I have to change the way I have been working so I can still get things done or shut down my sign shop permanently.

[Tom M King]

Keith, even commercial bridge cranes don't cost That much. I would think one would pay for itself pretty quickly with your sign business. I'm intending to put one in that shop out of components and steel that I get delivered for no shipping cost, but it's so full of stuff that I have to add on more space than is already there so I have somewhere to move stuff out to be able to install the parts.

[Keith Outten]

The nice thing about mag drills is that they don't take up any appreciable space and they are portable machines :)