Thread: 240 volt heavy duty 1/2" drill

Forstner bits in a decent battery drill should do it (they come up to 100mm dia if you have the dough).

you won't want to read this, but ...

forget it.

to achieve the vertical accuracy required for a mortice you will either need a stand or extraordinarily strong wrists and an accurate eye.

My suggestion is to get either a bench or floor mounted 10 or 12 inch drill press and make a table for it.

Thanks Fence furniture, unfortunately forstners bog up too much for that type of work, hence the choice of the promac bits. I see where you're coming from Ian, but the timbers I'm using are 10"x 10", 12" x 10" and below. So I need to bring the machinery to the timber, I was thinking of using a polished steel mirror with a hole in the centre to use as a guide to keep the drill bit on the straight and narrow (vertical).

Originally Posted by HUON

I see where you're coming from Ian, but the timbers I'm using are 10"x 10", 12" x 10" and below. So I need to bring the machinery to the timber,

so I surmise you are building a timber frame structure -- though 10" x 12" and 10" x 10" hardwood is approaching bridge or warehouse sized components.

Can I encourage you to first think about how you will handle the columns and beams for an efficient work flow before you think about the power tools you will be using.
If you are aiming to drill square to the face holes for your mortices, you will want to use a drill stand of some sort. To my mind arranging your work space with roller or ball stands so that the timber passes past a drill press will be far more efficient than clamping, unclamping, aligning and reclamping a portable drill stand.

Also, three rows of 3/4" drill holes will be easier to drill and require much less torque than a single row of 2" holes. But a chain morticer might be your best option.

Maybe a magnetic drill stand...Fasten a steel plate to the timber, place drill on plate. They are not hugely expensive being in the under $500 range.

if you are insistent on using a hand drill, look at the high torque offerings from
Makita model DP4003K and similar
Hitachi model D13VG and similar
DeWalt Milwaukee and Bosch will have similar offerings

BTW. as far as I can see 38 mm (1-1/2") is around the max hole size for these portable drills.

Firstly, how deep do you need to drill the holes, what sort of timber, and is it green or dry? (I have an idea forming)

For nature playground work we use the biggest brushless Makita for 3/4 - 1 1/4" holes x 300 mm long coach bolt holes and 2 x 5A batteries lasted all day. That drill could twist the head of those bolts if you pushed it too hard,

If you want a cheap 240V solution then a demolition hammer drill 1500W+ of power on plain drill mode is hard to beat. I've used my Ozito with those auger style bits and it fair rips through the timber. Watch out when they get stuck because they will twist your wrist off if you are not careful.

I was thinking along the same lines ie using smaller bits more often for hogging out. I'll still need my Barr chisels to clean up the mortise, whether I use a drill bit or chain morticer. And I still need a good quality power drill (help pease).

Metabo make a good drill. Admittedly my 30 yo brute was made in Germany, but I think Ratbag would still say that Metabo are the drills of choice (he seems to know all we need to know).

BE 75-16 are about the same price as the Makita Ian refers to. 750w, 75Nm, 660 rpm (which is a bit low for my liking), single gear

The Metabo B 32/3 https://www.metabo.com/au/en/tools/d...000-drill.html would be a bit easier to position vertically and should eat a 38 mm hole. And it has a clutch so if the bit jams you won't be spinning like Grommet.

Thanks for all that good info, 250mm (10") would be the deepest. It's radiata pine, milled green, airing for a few months. Crikey, I love therapy shopping.

Ps , low rpms are good. I'm too old to be a grommet. Another ps, I really am after top of the range gear that will see me into the ground.

Originally Posted by ian

The Metabo B 32/3 https://www.metabo.com/au/en/tools/d...000-drill.html would be a bit easier to position vertically and should eat a 38 mm hole. And it has a clutch so if the bit jams you won't be spinning like Grommet.

Yes I looked at that, and nearly linked to it, but it has a 65mm collar - doesn't fit my thought train (although it would be a monster of a drill).

So....using a Metabo Drill Stand with any drill that has a 43mm collar, you rotate the whole setup on the column around 180° so that the drill now points directly at the timber, not the drill stand base. Clamp the base to the timber, start drilling. It only has 65mm travel so then you release the holding thingo on the column (with the drill bit retracted back up) and slide the whole head down and drill again. By the time you've done 120mm hole you shouldn't need any more guidance to keep it vertical (i.e. drill freehand to finish).

My Metabo stand is also 30 yo, and it does not have a groove on the back of the column, so I can just rotate the head. If there is a groove you can undo the column at the bottom and rotate the column around.

I have used this method a number of times to get perpendicular dog 'oles, and it works very well indeed (each successive hole allows a new spot to use a clamp in to progress allow the row).