# Infinity Twist Adjustable Slot Cutter



## bfblack (May 2, 2012)

I am considering the Infinity Precision Twist Slot Cutting Router Bit model 61-512. Does anyone have any experience with this adjustable slot cutter router bit?


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## DesertRatTom (Jul 3, 2012)

Very interesting bit. Being able to change the width of the slot by a simple adjustment is very interesting. One bit for up to 1/4 inch slot, another for up to half inch. Adjustable in incriments of 4/1000 of an inch means you can cut to the thickness of the panel, tongue or spline. Looks very interesting. The pair is $250. I think I'd have to do a lot more of this kind of work to justify that. I do like that it has four cutters.


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## Cherryville Chuck (Sep 28, 2010)

I have a stacked cutter set that came with 1/16, 1/8, 3/16, and 1/4. I’m trying to think if I ever needed something in between and I can’t think of that happening. The set also came with a bunch of shims which is handy if you are using two cutters to make a tongue or short tenon. I think I’d still go with a stackable set rather than one adjustable cutter. I think the set is more versatile.


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## Hypnotoad (Apr 17, 2018)

DesertRatTom said:


> Very interesting bit. Being able to change the width of the slot by a simple adjustment is very interesting. One bit for up to 1/4 inch slot, another for up to half inch. Adjustable in incriments of 4/1000 of an inch means you can cut to the thickness of the panel, tongue or spline. Looks very interesting. The pair is $250. I think I'd have to do a lot more of this kind of work to justify that. I do like that it has four cutters


Really interesting and could be very handy but my router didn't even cost that. :surprise:


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## bfblack (May 2, 2012)

My woodworking club make doll beds for disadvantaged kids and the design requires a stopped dado of 9/32" wide by 1/4" deep. Each bed requires two of these dados that are over 10" long. One quarter inch Baltic birch plywood fits in the dado and if the plywood has much warp to it, a 1/4" wide dado does not work very well. My present approach is to make a single pass with a 1/4"x1/4" slot cutter followed by a 9/32" diameter straight bit. Since we make several hundred of these doll beds, we need to operate in a production mode.


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## Cherryville Chuck (Sep 28, 2010)

The last time I made dadoes it was for a set of Oliver’s to go in the fable of an attic. I decided to just throw together a stack of dado blades and the cut the tongues of the Oliver’s to fit. That turned out better and faster than any other way I’ve tried and you could do the same. 

Cut a slot with a standard 1/4” slot cutter and then set a table saw for 1/4” wife by that deep and size the tongues that go into the slots. I’m guessing that the ply is for the bottom of the bed so do it on the side that doesn’t show. Once the saw is set you can run a hundred through per hour at least.


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## Stick486 (Jan 4, 2013)

> for a set of Oliver’s to go in the fable of an attic.


?????


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## Cherryville Chuck (Sep 28, 2010)

Stick486 said:


> ?????


Set of louvers. For some reason spellcheck doesn’t know that word. For the gable in an attic. That part was typonese. If my text is off check the keyboard for the letters on either side of the one that seems out of place. Very small keyboard on iPhone and very large thumb or finger trying to tap it. Makes for a bad combination.


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## Stick486 (Jan 4, 2013)

Cherryville Chuck said:


> Set of louvers. For some reason spellcheck doesn’t know that word.


you are now the king of typonese....


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## Steven Owen (Aug 14, 2017)

The advantage is supposed to be quick set-up. Like anything, it’ll come down to how many projects you have that require cutting tongue & groove. 

If you do a lot of outdoor projects these would be more handy.


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## MT Stringer (Aug 15, 2012)

> fable of an attic


That sounds like one of Aesop's Fables!>


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## Cherryville Chuck (Sep 28, 2010)

MT Stringer said:


> That sounds like one of Aesop's Fables!>


Or the theme of a really bad horror movie maybe. If it’s a fable then the message is don’t put Oliver’s in your attic, put louvers in instead.


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## tomp913 (Mar 7, 2014)

Cherryville Chuck said:


> I have a stacked cutter set that came with 1/16, 1/8, 3/16, and 1/4. I’m trying to think if I ever needed something in between and I can’t think of that happening. The set also came with a bunch of shims which is handy if you are using two cutters to make a tongue or short tenon. I think I’d still go with a stackable set rather than one adjustable cutter. I think the set is more versatile.


When making flat panel doors, I cut the groove in the rails & stiles with two (or more) passes on the table saw, flipping the piece between passes. Use a piece of the same thickness to adjust the fence for the correct (slip) fit on the plywood panel. I bought a router bit that was supposedly the same thickness as the plywood but never got consistent results - either the plywood had a little bow or thickness variation which prevented the parts going together properly, plus the bit really needs to be a little larger than the plywood so that assembly goes smoothly. The other thing about the router bit is getting it exactly centered on the thickness - a lot of trial and error, so probably easier to mark all the outside faces and make sure you're always cutting from the same face. Doing the job on the table saw is way quicker, and the two pass method gives you a perfectly centered groove - and normally only a couple of fence adjustments to get the perfect fit. Because I'm still working with the Unifence, I cobbled together the set-up shown with my MagStop fence to give me pressure against the fence as well as down on the saw table while I was running the parts to cut the grooves.

The other thing I'd question, in case it matters, is whether these bits give you a square bottom or a curved one like the old wobble dadoes - might be a problem depending on where you measure to establish the size of the panel.


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## Herb Stoops (Aug 28, 2012)

Cherryville Chuck said:


> Or the theme of a really bad horror movie maybe. If it’s a fable then the message is don’t put Oliver’s in your attic, put louvers in instead.


I just thought you were celebrating your BD early, with some of that good Canadian Spirits.
Herb


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## bfblack (May 2, 2012)

Perhaps I did not make it clear that I am creating a STOPPED dado so a table saw approach will not be a good one. The attached jpg file is the exploded view of what I am making. I want to produce the stopped dado in the side boards. The through dado in the head and foot boards is made on the table saw with a traditional dado blade since the start and end of the dado is covered by the side boards.


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## Hypnotoad (Apr 17, 2018)

bfblack said:


> Perhaps I did not make it clear that I am creating a STOPPED dado so a table saw approach will not be a good one. The attached jpg file is the exploded view of what I am making. I want to produce the stopped dado in the side boards. The through dado in the head and foot boards is made on the table saw with a traditional dado blade since the start and end of the dado is covered by the side boards.


I see what your doing, when I do something like this I rebate the end pieces so you can't see the dado's and they don't need to be stopped.


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## Cherryville Chuck (Sep 28, 2010)

I really strongly suggest you try sizing the plywood to the groove instead of the groove to the plywood. Sizing the ply will give you reliable results every time whereas the ppposite will only do it if the plywood is very uniform. And it’s faster.


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## bfblack (May 2, 2012)

Thanks for your comment. The design shown has evolved from making a few thousand over several years. The side boards are nailed to the edge of the head/foot boards so that there is no dado visible. This requires a stopped dado in the side boards.


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## bfblack (May 2, 2012)

Thanks for your suggestion. The plywood we use is 1/4" Baltic (Russian) birch and it is of good quality and the thickness is consistently 1/64" under 1/4". If the plywood was perfectly flat, then a 1/4" router bit would be just fine. The milling of the piece parts take place over months so you can't rely on the plywood being flat at assembly time, even if it started off perfectly flat. The collective experience of our woodworking club is that the Baltic birch plywood is consistently better than US made plywood. I am aware of Apply Ply but it is not available locally in reasonable quantity and/or price.


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## Cherryville Chuck (Sep 28, 2010)

A 64th under sounds more like 6mm than 1/4”.


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## bfblack (May 2, 2012)

Cherryville Chuck said:


> A 64th under sounds more like 6mm than 1/4”.


As with most sheet goods, you better measure their thickness before using them. I checked the thickness of thickness of the Baltic Birch plywood I am using and it was 5.9mm, which is 0.1mm (0.004") less than 6mm. Since the plywood was of European origin, it was likely made to a metric standard. When I go the local (US) hardwood lumber yards, they tend to speak 1/4" instead of 6mm.


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## Cherryville Chuck (Sep 28, 2010)

Most people in the US don’t realize just how “metrefied” you’ve already become. Only 3 countries in the world still use Imperial measure. If you are using imported goods then it was made to metric standards. It may be a metric equivalent of an Imperial measure but sometimes it’s metric and sold as the closest Imperial equivalent. In this case it probably started out as 6mm and then got a light sanding to get the 5mm. The same process happens with US finish plywood. That’s why you can buy undersize bits.


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