Boring Long Holes in Timber(25mm)

[Cole]

Does anyone know of any tools designed and built to do long accurate bores in timber lengths of 3+ meters? Timbertools.com has a Zobo system that will do bores that long but it runs at a cost of $10k. Looking around has led me nowhere.

[jamie shard]

You might want to look at "gun drilling", as well as "shell" or "nose" bits. Here is some interesting reading:

http://toolmakingart.com/2011/02/27/how ... ing-guide/
http://www.guhring.com/documents/catalo ... eflyer.pdf


My guess is that you could make a shell auger out of a rod, drill a small guide hole through your timber, then chase it with larger and larger drill bits.

Just thoughts, i've never done it.

[Chris Hall]

I've seen a similar device to that Zobo deep drilling system at a commercial shop near where I live. They built it themselves, using readily available 80/20 extrusions, and so forth. Some fabrication was definitely involved, and I don't know how much it cost. And for long holes, the minimum drill size seems to be 1.25" or so.

I ran into this issue when wanting to drill a wire chase through the shrine lantern post. I ended up making the post out of four sections which joined to one another, milled so as to leave a hole up the middle.

If glue were an option, then a timber could be bandsawn along the centerline, a core box bit used on each half to mill a trough, and then the surfaces cleaned up and glued back together, leaving a hole up the middle.