Lock Miter Bit setup

[Alan Schaffter]

I think few people will disagree that the lock miter bit requires a very accurate, and often difficult and very frustrating two-part setup- bit height and router table fence position must be set precisely. I found instructions available from various manufacturers and vendors were often incomplete, limiting, hard to execute, and sometimes downright wrong. Profile matching set-up blocks only work when the stock is the same thickness as the block- not all stock, especially ply, is exactly 3/4", the thickness of most blocks! Also, few (none?) of the instructions work if the thickness of the stock on each side of the joint is different.

A few months ago I hinted that a simple new solution was on the way. Well it is time to dig out and dust off your lock miter bits. I'm happy to say the solution has arrived with the release of the Infinity Lock Miter Master earlier today.

The Infinity website has more images, a video, and a link to the manual which shows the full range of lock miter joints made possible with this unique new patent pending set-up jig.

[Bill Huber]

So here you go again making me spend more money, was the I-Box enough.....
Looks like a very good setup tool.

[Tom Willoughby]

I am definitely going to check this out as I find that the lock miter bit is one of the most finicky set ups going.

[Alan Schaffter]

So here you go again making me spend more money, was the I-Box enough.....
Looks like a very good setup tool.

Bill, If you decide to get the set, I hope you like it as well as the I-BOX. Thanks for your kind words and super reviews.

They are both "jigs" but talk about being at the opposite ends of the complexity spectrum!!!

I have about a half dozen things in the works, and have even had to deal with a few rejections on some- its not all roses. But once I get caught up with yard work and take a little vacation, I'll get back to work on one or more of my designs. I would like to be able to have a few more widgets on the market before I call it quits.

For any who care, I don't set out to invent things. During a project, tool repair, etc. I sometimes get a feeling there has to be a better tool or better way to do a particular task. That gets my mind racing- sometimes even in the wee hours of the morning. It doesn't always result in something or sometimes results in just a shop tip. But sometimes the light bulb goes on big time and I pursue the idea until I determine either it just won't work or maybe I have hit on something. If I think it is a good idea, I make a primitive prototype to verify the concept. And sometimes, I hit on an idea that I think is so good that maybe I can market it. Usually during the process of preparing a brochure or during manufacturing feasibility I come up with enhancements- that happened with the I-BOX and resulted in integral calibration, micro adjustment and the ability of the jig to do decorative insert joints. With the Lock Miter Master it was the secondary reference marks and ability to make joints in stock of different thicknesses and off-set joints.

Since I am a semi-regular here, I'll watch for questions and do my best to answer PMs.

[Chris Padilla]

Found the video on YouTube but it doesn't go into different thickness cuts...which I assume the extra lines on the jig are for:

[Chris Padilla]

Alan,

Tell Infinity they need to do a slightly better job of describing the difference between a "large" and "small" lock miter bit. Ouch, $8 for shipping!!

[Alan Schaffter]

The reason for two sizes of the Lock Miter Master setup jig- Infinity and some other manufacturers (Frued, etc.) make a small lock miter bits that can be used on stock as thin as 3/8". While one Lock Miter Master jig could have been made to cover the full range of bit sizes, it would impact the router plate insert opening you can use and might make setup slightly more difficult.

As to the capacity of the Lock Miter Master jig set- Infinity's Lock Miter Jr. bit (like the Freud Baby #99-035) can be used with stock that is between 3/8" - 3/4" thick, while the Lock Miter Sr. covers stock 5/8" to 1-1/8" thick (handles thicker stock than most). So the Lock Miter Master jig set will definitely work with any Lock Miter Bit (or shaper cutter) that is designed to handle stock thicknesses from 3/8" - 1-1/8". You may need to look closely to find those dimensions in the manufacturer's lock miter bit description.

The Lock Miter Master can likely be used to set lock miter bits designed for stock outside that range, especially bits designed for thicker stock, if any exist. Note: the shape of the profile doesn't matter- some lock miter bits have more pronounced male and female profiles, while others are stubbier, little more than a bump and valley- it makes absolutely no difference to the Lock Miter Master.

I hope that answers the size questions.

[Alan Schaffter]

Found the video on YouTube but it doesn't go into different thickness cuts...which I assume the extra lines on the jig are for:

Chris,

The video just gives a short glimpse of the Lock Miter Master in operation.

The extra lines are used when making off-set lock miters which allow you to round over a corner without having the miter line exposed or exposing plywood interior cores. It is also useful when making drawer fronts. One set of small lines (1 line = 1/16" offset) is used for an offset on one side of the joint and the other set of small lines for an offset on the other side of the joint. A dual offset is possible and results is a rabbet in the middle of the corner.

If you go to the Infinity website LMM page you can click on and view the full manual in PDF. It has procedures for and drawings showing how to use the LMM to to make all the lock miter joints (except the dual offset).

Drawing of an Offset Lock Miter with 1/8" of offset:



Actual Off-set Lock Miter Joints (corner not rounded):





Extreme (1/4"?) offset:



Drawing of a Dual Off-set Lock Miter Joint (with an insert made from contrasting colored wood):

[Ole Anderson]

Do they work on any lock miter bit, or just the ones from infinity?

[Mark W Pugh]

OK, looking at the Infinity site, http://www.infinitytools.com/Lock-Mi...products/1062/, I don't get the 2 piece set (00-LMM). Are they the same as the small and large jigs? For some reason I'm not seeing the likeness of the jigs (00-LMM vs LMM-002/003). Thanks.

[Alan Schaffter]

Do they work on any lock miter bit, or just the ones from infinity?

Ole, we haven't checked every bit, there may be a strange, super-sized, or miniature bit out there we don't know about, but the Lock Miter Master should work with ANY brand of lock miter router or shaper bit. The LMM takes advantage of the basic geometry of these bits, not the overall size or particular mating male/female edge profiles, which differ slightly from manufacturer to manufacturer.

OK, looking at the Infinity site, http://www.infinitytools.com/Lock-Mi...products/1062/, I don't get the 2 piece set (00-LMM). Are they the same as the small and large jigs? For some reason I'm not seeing the likeness of the jigs (00-LMM vs LMM-002/003). Thanks.

Mark, in addition to their normal size bit which will cut lock miters in stock 5/8" to 1-1/8" thick, Infinity makes the smaller Lock Miter Jr. which is designed to be used with stock 3/8" up to 3/4" thick. It is similar to the Freud Baby lock miter bit. If you are using one of these little lock miter bits, a small router table insert ring could interfere with the standard LMM (LMM 003) jig during setup. For that reason, Infinity decided to make available a small version of the Lock Miter Master setup jig- the LMM 002. If you don't have or plan to get one of the small lock miter bits all you need is the larger jig (LMM 003) which is available individually as is the small LMM 002 (look at the bottom of the lock miter bit product page.) To cover all bases, get the set (especially since it's on sale ).

[Chris Padilla]

The reason for two sizes of the Lock Miter Master setup jig- Infinity and some other manufacturers (Frued, etc.) make a small lock miter bits that can be used on stock as thin as 3/8". While one Lock Miter Master jig could have been made to cover the full range of bit sizes, it would impact the router plate insert opening you can use and might make setup slightly more difficult.

As to the capacity of the Lock Miter Master jig set- Infinity's Lock Miter Jr. bit (like the Freud Baby #99-035) can be used with stock that is between 3/8" - 3/4" thick, while the Lock Miter Sr. covers stock 5/8" to 1-1/8" thick (handles thicker stock than most). So the Lock Miter Master jig set will definitely work with any Lock Miter Bit (or shaper cutter) that is designed to handle stock thicknesses from 3/8" - 1-1/8". You may need to look closely to find those dimensions in the manufacturer's lock miter bit description.

The Lock Miter Master can likely be used to set lock miter bits designed for stock outside that range, especially bits designed for thicker stock, if any exist. Note: the shape of the profile doesn't matter- some lock miter bits have more pronounced male and female profiles, while others are stubbier, little more than a bump and valley- it makes absolutely no difference to the Lock Miter Master.

I hope that answers the size questions.

Actually, I meant to for them to do a better job of describing the different sizes for the JIG...not the lock miter bit itself. I misspoke/typed. However, I see they added some information to the description for the two sizes of the jig so great! Thanks!

[Tony Rodoracio]

Alan,

Any plans for the same type jig for the 22 1/2 degree lock miter bit?

[Alan Lightstone]

Just made you and Infinity a few bucks. Since we're both in Tampa Bay, hopefully should get mine soon.

Nice job as usual, Alan.

[Alan Schaffter]

Alan,

Any plans for the same type jig for the 22 1/2 degree lock miter bit?

Funny, you should ask! As you may know a 22.5° lock miter joint requires two separate bits* to create. I have a design for a jig that can be used to set both bits. Like the Lock Miter Master, it can be used with any thickness of stock (within the range of the bit). For all those wondering, the length of the 45° or 22.5° angled cutting edge (more accurately the height) determines the maximum thickness of stock that the miter bit can handle.

*I also designed a single bit that will cut both sides of a 22.5° lock miter joint, but it comes with one compromise- it leaves a small void in the middle of the joint. The void can only be seen from the end grain and it doesn't reduce the strength of the joint.

As you might suspect, that bit could be difficult to set, UNLESS . . . . you guessed it, you use a special jig, like the Lock Miter Master; I have already designed one of those!

All that being said, and I may be wrong, but I don't think the 22.5° lock miter joint is nearly as popular as the 45° lock miter joint. I don't know if there would be sufficient retail demand for a set-up jig for the current crop of 22.5° lock miter two-bit sets or for my 22.5° single bit and corresponding setup jig, to justify possible manufacturing costs and/or retail price. Only time will tell.