Dowel Construction Advice
A cabinetmaker who has just invested in a horizontal boring machine gets help making the transition to dowel construction. August 22, 2013
Question
I recently bought an Accusystems hpp cnc horizontal bore machine. We are making a big move into the dowels construction style and I had a few questions. Hopefully someone out there runs a machine similar to this and can give me some setup pointers. On vertical members we will drill on the nested based router.
Do most of you use a bar coding method at the dowel machine for mating holes or do you set up several standard boring scenarios at the machine interface? Also, any general dowel tricks are much appreciated.
Forum Responses
(Cabinetmaking Forum)
From contributor C:
Can you post to it and what software are you running? We have a 23 spindle fixed and stay with 6 dowels in a 24 base and skip 96mm. Eight in a wall and hit it every 32mm cause we can't post to the doweler. If it were cnc I would program it parametrically and move on.
From the original questioner:
I think the parametric will be the way to go. I run cabinet vision and it certainly has the capability for that also. How far do you normally leave the dowel sticking out? On the pre-glued dowels do u just spray water on them before assembly or do you use a metered amount? I'm thinking of starting my first and last dowel 25mm from each end and including one every168mm? Is that enough?
From contributor C:
Thirty seven mm from the front. We are hands gluing right now the few we glue together with the finished ends. I sink them at 25mm in the decks and wall shelves and 15mm in the case sides leaving a 2mm for play (38mm x 8 mm dowels). I think 25mm might be too close to the edges.
From contributor D:
There are lots of things to consider. You need to consider the configuration of both your nesting machine and your dowel machine. Will your nesting machine be drilling multiple dowel holes in a single drop or just one at a time? What is the drill insertion spacing on your dowel machine? I had mine built (Omal) with 64mm spacing because that is what my vertical drill layouts are based on. Most machines I have seen are either 32mm or64 mm drill to insertion centers so neither one would do 96mm spacing well nor do they do odd spacing well since that requires the machine to drill the hole then move over and do the glue and insertion. The fastest parts for me are the ones that end up with all 64mm centers. You can hardly keep up with loading each side of the machine. I have one parametric program in the dowel machine that does 98% of my dowel layouts, I just need to input the field length on each part.
You can use a bar code reader to access programs you have written in your dowel machine or to access programs from your post processor if it will write to your dowel drill. That might be worth doing if you are labeling the parts now and can add bar code. Omal also offers a Laser set up device, do not know if others have that or not. If you set up your doweling programs correctly you will hardly need to ever write new ones. I have not even gone into the editor in my dowel machine for almost two years now.
You will probably need to try different methods of watering the holes. I went from squirt bottle to Dosicol to mister. Now I use a spray bottle with a little hose on the end and an atomizing nozzle, that is the quickest for me and seems to wet the hole well. We use 8mm x 35mm dowels that I leave sticking out 12mm, rule of thumb is 2/3 into core of panel and 1/3 in end.
I use 8 dowels in a 610mm base first dowel 25mm from front and 39mm from back since we use 1/2" backs inset 16mm from wall. My upper cabinets end up with either 5 or 6 dowels depending on depth.
From contributor L:
If you are making kitchens you should be able to limit the number of patterns needed to just a few. Omal has a good system for being a quick auto setup. I think 25mm from edge is a bit too close. If you are using pre-glued dowels be sure to cover the hopper so they don't collect dust. Dust will reduce the hold. We use glue and still cover the hopper with a shower cap looking plastic. Try to limit moisture changes in the dowels. Store the extra dowels in air tight containers.
From the original questioner:
A lot of good ideas here! Contributor D you said "I have one parametric program in the dowel machine that does 98% of my dowel layouts, just need to input the field length on each part." Are you saying if you have a 24 inch deep part you are inputting 24 and the program takes it from there?
My program will post to the machine however at a cost. I think I am going to try to stay away from that for the time being and see if I can figure it out. I read somewhere that AWI specs say the first dowel has to be within one inch of the end of the part. That was the only reason I was thinking of going with 25mm to the first dowel. However, now two people have said start at 35mm. I guess I will play with that to see what works best. I have heard Chicago dowel is the best dowel, any thoughts?
From contributor D:
Actually 610mm, but yes. AWI calls for 37mm maximum for the first dowel or confirmat. I used to set the first dowel at 20mm and had no problem but when I started inserting dowels before banding I needed a little more room. My Holz-Her has no problem banding with dowels set at 25mm.
When I add confirmats I put the first one between the first two dowels spaced at 64mm. Now this puts the confimat at 57mm but the dowels actually do the work. The confirmat is just in place of the case clamp for cabinets we want to send out un-assembled. I always like the first dowel closer to the front in case of warped material. Thirty seven always seemed to allow too much misalignment. I have had them at 20 or 25mm for over 20 years now.
