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Discussion Starter · #1 ·
Hello,

New here and wasn't able to find anything related to my problem. I got a solid finger joint bit.

I run the edge starting from it's left side to it's right. Now when I assemble the workpieces one side will fit Ok but the other not so much. It's like if the bit cuts gradually bigger fingers as you move the workpieces (maybe only 1/16 inch but enough to cause problem). I assume that something must be off on the router table but can't seem to figure what or maybe i'ts the bit itself?? keep in mind that this is a 30$ bit.

Anyone had a similar problemn or could point me the problem.

(sorry for my English)

Thanks
 

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Welcome to Router Forums. Now that you have joined us, please take the time to edit your profile. Go to "Edit Profile" in the upper right below your Logon and tell us a little about yourself and the name that you would like us to call you. A rough idea of what part of the World that you live in would help too.

"Finger Joints" can mean two things in woodworking because the media can't seem to standardize the names. To me, a finger joint is comprised of long tapered pins on the end of two boards that when assembled with glue, form a longer flat board. The other joint, to me, is square pins and equal sized square spaces between these pins, cut into the ends of two boards so that when they are assembled together they form a strong corner joint, as used in box building. In either joint, the cuts must be made with close tolerances so that the two pieces will fit together properly I'm asking which joint you are trying to make because the two joints are frequently called the same thing.

If trying to use a router bit in a router table to cut either of these it is frequently necessary to use feather boards to hold the stock against the fence and table so the cuts can be made accurately. Very careful positioning of the blade or bit as well as the wood is necessary when making the repeating cuts needed for longer joints.

Others will be along soon to also try to help. Your English is fine. I just need a better explanation or a picture to see better what you are trying to do. You should be able to post a picture if it's on your computer. Click on "Go Advanced" at the bottom of your post, then follow the instructions to add the picture from your computer to the end of your post.

Charley
 

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Hello,

New here and wasn't able to find anything related to my problem. I got a solid finger joint bit.

I run the edge starting from it's left side to it's right. Now when I assemble the workpieces one side will fit Ok but the other not so much. It's like if the bit cuts gradually bigger fingers as you move the workpieces (maybe only 1/16 inch but enough to cause problem). I assume that something must be off on the router table but can't seem to figure what or maybe i'ts the bit itself?? keep in mind that this is a 30$ bit.

Anyone had a similar problemn or could point me the problem.

(sorry for my English)

Thanks
Your English is very good. Seems if your jig is not quite right it will gain width as you cut. Sometimes only few thousandths on the first cut next double that and so on til the end one is X times larger than the first.
What kind of jig are you using and is the bushing on the router the right size/or are you on a router table and using a box joint jig?
You might try turning one piece over when you assemble them and see if it is tighter, that will tell you if it is your jig.
Also you might measure the bit with a digital Caliper to see if it is the correct dia. I have found that some manufacturers call a .245" bit a 1/4" bit. Also check to see that you are not mixing metric and/or imperial inch bits or bushings.
Just some suggestions,
Herb
 

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The older name for the tapered finger joint was a splice joint since that was all that that type joint is used for, to splice the end of two boards together to make a longer board. If the thickness of all the fingers change then the individual cutters must be spreading apart a bit from the pressure of the cut. Otherwise I'm wondering if the board is lifting up or pushing down and not making a perfectly horizontal cut?
 
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Discussion Starter · #6 ·
Hello everyone an thanks for taking the time to respond i appreciate it.

The finger joint I am refering to is the one you would use to make a butt joint not the box joint with big finger

Since I cannot post a url yet the bit i am talking about is a solid finger joint router bit. Yonico makes this type of yellow bit. I am refering to the one with four cutter that cannot be removed.

My bit seems to be making fingers that are too big leaving the joint open. I have somewhat been able to solve my problem by lowering my bit by about 1/64" 1/32" then recutting the joint again but arent these bits supposed to cut the joint right without ajusting everytime.

Since it seems to be coming from china maybe it's not perfectly shaped.

I wonder if anyone have experience using those bits

Thanks everyone
 

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I have this one: https://www.ebay.ca/itm/380447121420?item=380447121420&rmvSB=true

I got it cheap on ebay not knowing if I would ever have a use for it or not. I tried it once just to see what it would do and I think it went together okay but it takes so much of a cut that it needs to be done in several passes using a miter sled of some sort so that you can control the depth per cut easier plus keep it square and resist the tear out. How did you run your piece through?
 

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Discussion Starter · #8 ·
Thanks cherry this is the kind of bit I am refering to.

Normaly they are sold a being able to cut a perfect joint without ajustment but clearly it seems that the one I got cuts fingers that are maybe a little bit too big.I solved the problem by finishing the first cut on both pieces than lowering the bit by 3/64" and the recuting both pieces.

I have now ordered another one wich you can remove the cutters. Since they cut horizontal finger vs pyramid shaped onea i assume they will fit better but I will have to wait to try it.

Hope to receive it soon then report back
 

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Discussion Starter · #9 ·
Update:

I have received my new router bit and it seems to have solved most of the problem.

I got one of those ajustable bit.(https://goo.gl/images/kPoHnX)

It works really well. I can cut full depth on a single pass without any difficulty. The only problem I can see now is that the fingers are now a bit too small and they fit a bit loose. I still think that with enough carpenter glue it will do the job.

I suppose that at 40$ you get what you pay for. I would assume that the same bit at 250$ would fit probably just perfect. I wonder if anyone tried one of those really expensive ones?
 

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You might want to look at a gap filling glue like Lee Valley's 202GF with a higher solids content than average glue (the GF stands for gap filler). If the fit is loose don't use polyurethane glue, they require a tight fitting joint to work. If it has to be water proof then you may have to go with epoxy and maybe some filler compound in it.
 

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This is a shot of the one that I occasionally use. It was a low cost one and the spaces between the cutters varied so I dismantled it and sand papered the paint from the touching surfaces but I still had to fit a shim between two of the cutters to enable it to produce good fitting joints.
 

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Thanks everyone

Harry i think i got the same bit as you. What did you use to shim the cutter.

I was thinking about screw washer but there is not a lot of space to put anything else on the shaft
For many years I've been collecting thin bits of metal and washers. Some are not much thicker than a couple of thou. They come in handy for all manner of things including setting cutters exact height on my metal lathe.
Here are two shots showing how I set-up the bit.
 

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