Thread: Dowelling accuracy

i haev been having similar problems. i just wobble the drill a hole bigger than needed and fill it with epoxy and place teh dowel in wile wet.

im sure there is a better answer but thats just what i do.

Originally Posted by Ian Smith

to use those brass plugs with the centre spike that Haron make which, in theory, allow you to locate the exact place to drill into the surface.

Ian

Make sure you use the right drill bits as these dowel points are imperial, if you use a metric drill bit you will have problems.

Originally Posted by Ian Smith

after drilling the hole in the surface at the spot indicated by the spike I am almost invariably out by a half a mm or so, in a random direction from the desired position, when I join the rail to the flat surface using a dowel.

After having marked the spot with the dowell points use a good centre punch to clearly mark the spot, this will guide the drill bit to make an accurate mating hole.

Peter

instead of using a standard drill bit I use a brad pointed bit with the point on the drill you place it in the hole made by the dowel points.
This works with what I make which are frames
regards Michael

Hi Ian

Two ideas that come to mind:

Firstly, if using the spike, the problem appears to be the drill bit wandering from the mark. Therefore use a more reliably accurate drill bit. I would suggest a brad point bit.

Secondly, if your result is a 1/2 mm off, just trim the dowel slightly so that you have a some adjustment, and then use a gap-filling glue, such as epoxy.

Regards from Perth

Derek

G'day Ian,

If you are accurately placing the rail on the face to make an impression with the dowel centres, can you not make a dowelling jig out of a hard timber that will
1)slip onto the end of the rail allowing you to drill guided holes in the end
2) then be held on the face of the other work with d/s sticky tape correctly referenced to the future position of the rail allowing guided holes to be drilled in the face
3)use bullet tip drills that are even more positive than brad point bits.

Hope that makes sense

Cheers
Michael

Thanks for the quick responses gents,
Weisyboy - Yep I've done that but it's a bit brutal and not always enough
Sturdee - I'm using the bit and dowels made by Haron so I have to suppose both are the correct size.
Coffenup - the Haron drill bit has a brad point - just not as pronuonced as some, presumably so you can go as deep as possible without breaking through the opposite face.

Ian

Originally Posted by Ian Smith

Sturdee - I'm using the bit and dowels made by Haron so I have to suppose both are the correct size.
Ian

Ian it's quite possible that one of either the drill bit, dowells or the dowell points are different, best to check rather than assume.

I have used the dowell points a number of times and I haven't had any problems but I use my own drill bits.


Peter.

oooo - too fast!!
Derek - As I indicated the Haron bit has a small brad point but that aside I had considered your suggestion of trimming the dowel - it just seemed a bit agricultural to me but since you (in particular) are mentioning it as a option I may weaken

Michael - I had given some consideration to something along the lines of your suggestion and I may very well go that way.

It is interesting that other have experienced this problem so I'll give this post a little longer to see what else surfaces

Thank you both

Ian

Sturdee - Thanks for your response - the dowels I have are an interference fit in the holes I drill so I assume this to be an indication of correct size and that's where the problem arises- if the fit was sloppy (not the point of a dowel as I currently understand it) then a bit of adjustment would be possible but it's because they are such a good fit that the holes must be exactly aligned.

So just to make sure we are not talking at cross purposes here it is my uderstanding that dowels should be a snug fit or is this incorrect?

Ian

Ian, why do you think you can't use a commercial jig? The Dowelmax jig (www.dowelmax.com) is capable of joining just about anything.

I'm not sure I understand the requirement. Is it something like shelving, where one part of the joint butts into a large flat surface? Can you describe it in a bit more detail?

Ron.

Ron,
I am attempting to run a number of rails from the face of a cabinet to the rear to support drawer runners.

As far as I was aware all the commercial jigs are designed to create butt joins or corners but after watching the slide show on that link you provided it looks like this beastie just might be the answer to a maidens prayer as it seems pretty clear they claim to be able to do what I want as evidenced by the mid shelves in that cabinet and the lower stretcher in the chair.

So thank you for that - I'll go looking for where in Oz I can obtain said beastie or perhaps you or some other forum members may know and pass it on

Thanks again

Ian

Hi Ian,

There's some bodgy suggestions there on how to get this right and some of them involve very crude approaches. The necessary approach is to decide initially to do the job properly not to find some bodgy compromise.This is cabinetmaking work not the work of mine carpenters setting up roof support!!!

My suggestions are:

Mark the dowel centres with a scratch awl or a Stanley knife and a good marking guage on the basis of precise measurement with a steel ruler.

Indent the centres about 2mm with the point of the scratch awl

Drill the dowel holes with a high quality centre spur bit such as the Stanley Powerbore and preferably but not essentially in a drill press.If you havent got that sort of drill bit you will have to make up a couple of jigs and drill in the drill press with Forstner bits. Spade bits are hopeless for this task don't even try them

That will give you a level of precision of better than 0,5mm.

An alternative probably not avaialble to you is to use the the Festool Domino rig.They are pretty accurate id used carefully certainly better than 0.5mm

I've got a couple of good quality dowelling jigs but my experience is that the use of
(designe for metal) twist drills can't give the precision you need. Old Pete

Originally Posted by old pete

Hi Ian,

There's some bodgy suggestions there on how to get this right and some of them involve very crude approaches. The necessary approach is to decide initially to do the job properly not to find some bodgy compromise.This is cabinetmaking work not the work of mine carpenters setting up roof support!!!

Careful, you'll start a fight

Yeah, I think the nub of the problem is the drill bit and, although I've never used one, those forstener bits look the goods. The Haron bit has a centre spur but they still tend to wander when used in a hand held power drill and I can't use a drill press inside a cabinet carcass.

What I think I'll do is try to make a small jig as mic-d suggested.

I did go searching for the Dowelmax mentioned by Ron Dunn, and there are some threads on this forum, one makes a comparison with the Domino, but they are a tad expensive.

Ian

These are the bullet point drill bits I was talking about. Don't see them much in Australia, don't know why.
These are imperial. You're welcome to try them if you still have trouble.

Cheers
Michael