Half Blind Dovetails on Incra/Jointech Systems – A Question

[Glen Blanchard]

I am toying with half-blind dovetails on my new Jointech system, and have a question for those experienced with making this joint on either of these systems (as they are very similar). My question is regarding making the cuts in the drawer front – which lays down flat on the router table. When I make this cut, (even though I am using a rubber soled push block) once the bit engages, the wood is pulled into the bit with a great deal of force – until it meets the stop block. Not much fun. This is a climb cut, no? In any event, I lose my ability to move the stock slowly, and thus the cut surface is not as smooth as I would like. As a result, my joints sometimes do not fit as precisely as I would like. I assume others experience the same thing. Is this just a matter of practice, or are there some tips someone would like to share with me?

[tom crawford]

I have the Incra and do not have this problam. You should be feeding the work piece from the right (as you face the fence) not from the left.

Tom Crawford
Selma, Oregon

[Mike Goetzke]

I've made several half blind DT's on my Incra jig. I have only used baltic birch ply though and have not had a problem with the stock being pulled to the stop. This should not be a climb cut - the stock should have a tendency to be pulled toward the fence. If the drawer face has enough area I try to use two push blocks. I had a video on how to use the jig and it is suggested not to rid the push block against the fence - this is to make sure the wood is securely against the fence.

Hope this helps.

[Glen Blanchard]

Well, I just tested a different species of wood. I will play with this some more tomorrow, but the cherry I just tested did not exhibit this pulling force. The piece that I had the problem with was a piece of curly ash. Perhaps it is the ash. I'll find out tomorrow. I would not have thought that different species would exhibit such different behavior though.

[JayStPeter]

I've had this problem in the past. Most likely it's your feed technique. I find that if I give the piece any slack at all it will pull. I use a push block on top and another push stick in the other hand to hold it tight against the fence. It has helped me, but I still have the problem occasionally. It seems especially bad with BB ply.

[Larry Crim]

I have had the same problem when I started using the Incra but since I always use the right angle fence with scrap clamped to it as you would if you were making the dt and use it as the push block this allows you to keep the drawer front firmly against the fence.
Larry
edit
Sorry I misread the ? I thought he was refering to the relief cut where it met the drawer front.

[John Lucas]

Glen,
You didnt answer Tom's post. It is key. You should be feeding the drawer front with the back down and flat on the table with a pushblock on it and you should be going left to right with the stop set accordingly. This is not a climb cut. It may be a difficult cut with a dull dovetail bit. The groove will tend to load with sawdust so you may have to make two passes at each point. You can hear when that happens.
http://www.woodshopdemos.com/incra324.jpg

Here is the procedure: http://www.woodshopdemos.com/dts-incra-2.htm

[Glen Blanchard]

Glen,
You didnt answer Tom's post. It is key. You should be feeding the drawer front with the back down and flat on the table with a pushblock on it and you should be going left to right with the stop set accordingly. This is not a climb cut.

Thanks John. Yes, I am moving the stock just as described and as in your image. The reason I thought this might be considered a climb cut is because as the cut is made, there is stock between the bit and fence. Guess that was a dumb thought, as this is no different than cutting a dado on the router table. Oh well. Although this is not a climb cut, I would think that it is this stock between the bit and fence that has a tendency to pull the stock into the bit.

In any event, I made many cuts today with cherry with much better results and less "pull". The ash I was using last night is not nearly as easily controlled as the cherry.