# bit question - inside groove, advice plz...



## rpludwig (Nov 22, 2011)

Another upcoming project...bit question:

Picture a small three sided box 2" x 4", like a small jewelry box but not, open on top and bottom, then insert a thin plexiglas top and bottom from the rear of the box. Need to rout a grove around he inside perimeter to accept the plexiglass (slide in from the rear of the box).

I'm sure there is such a groove cutting bit out there, just haven't found one. A link would be helpful.

Thanks in advance!

Ron


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## harrysin (Jan 15, 2007)

rpludwig said:


> Another upcoming project...bit question:
> 
> Picture a small three sided box 2" x 4", like a small jewelry box but not, open on top and bottom, then insert a thin plexiglas top and bottom from the rear of the box. Need to rout a grove around he inside perimeter to accept the plexiglass (slide in from the rear of the box).
> 
> ...


Ron, although I can't visualise what you have described, it doesn't alter the method of routing the grooves, which must be done of course before assembly. the type of joint that you use will determine if the groove can go all the way across the pieces or, if, because of the type of joint the groove will show, you will have to stop the grooves before reaching the ends of the pieces. The bit will have to be the same diameter as the material that will slide in the grooves, or very slightly larger.
Some people prefer to use a slotting bits but one costs more than a small dia. bit.
The second shot shows a couple of slotting bits.


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## OPG3 (Jan 9, 2011)

Ron, I have some preserved insects in (4- sided) boxes _similar_ to what you have described. I'm also not certain if I am understanding what you're driving at, but usually the museum display cases have two pieces of transparent material (glass, lexan, plexi, etc) separated by thin strips that are between the glass and adhered to the exterior frame. In some cases, you may find it advantageous to groove your wooden sides prior to attaching the corners together - this would be done "pinching" the two panes of transparent material as corners are joined together. *OPG3*


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## rpludwig (Nov 22, 2011)

Harry, Otis...thanks for your replys...

I'll try and describe this project better...

A box created by plunge routing out the entire interior of a block of 5/4 x 2" x 4" wood, no top, no bottom, and no back, so it's a 3 sided u shaped square workpiece. The top and bottom are then created by sliding the plexi into grooves near the top and bottom. The back is a flat piece to "close" the box, also grooved to accept the rear of the plexi. The bits in Harry's pic are on the right track...the depth of the groove would be only approx 1/8" or less. I assume the challenge would be how to address the front inside corners, although the plexi could be slightly radiused at that point, since the depth of the groove would also be radiused as the bit reaches the inside corner... I've seen Harry's coin trays with the decorative groove routed into the perimeter...basically run a similar bit on the inside of he box...

Hope this makes it more clear...


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## OPG3 (Jan 9, 2011)

*A possible approach...*

Ron, I better understand, now - from your latest description. I made a drawing for you (thinking otherwise), but I think the lower of my two sketches may  still be able to apply. If I were doing this, I would go for an appropriate keyhole bit - approached from each surface (top/bottom). Good luck, *OPG3*


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## rpludwig (Nov 22, 2011)

Otis...you got it in the bottom dwg, all one piece, no strips...thanks so much for doing that...!

Not familiar with keyhole bits, but will do a search...

Ron


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## Mike (Nov 22, 2004)

Ron, there is no way to insert your plastic into a solid box with grooves. This job is easy with a box that is glued up. Get a piece of wood that is longer than the lengths of the sides added up, rout your grooves on both sides, cut the pieces to length and glue the box up with the plastic and items you want inside in place.


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## bobj3 (Jan 17, 2006)

Hi Ron 

They make a VERY small OD slotting bit just for that type of job, it's about 3/4" OD cutter with a bearing on it.. many picture frame makers use them..

I will need to dig for the link for it..


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## rpludwig (Nov 22, 2011)

Mike said:


> Ron, there is no way to insert your plastic into a solid box with grooves. This job is easy with a box that is glued up. Get a piece of wood that is longer than the lengths of the sides added up, rout your grooves on both sides, cut the pieces to length and glue the box up with the plastic and items you want inside in place.


r u sure? it's 3 sided piece with the back installed after the plexi is inserted...(unrelated to the current project).


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## bobj3 (Jan 17, 2006)

Hi

I didn't find the one with the bearing on it but it looks like the ones below..

Woodline USA - T Slot Cutters
Small Solid Carbide Keyseat Cutters

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## rpludwig (Nov 22, 2011)

Bob, on the right track with that t-slot cutter...I'll keep hunting for similar w/bearing.

Thank you!!!

Ron


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## OPG3 (Jan 9, 2011)

*Another view...*

I see why some think the transparent parts will be difficult to install, but with only 3- sides - there will be no problem. You can use a keyhole bit without a bearing if you use a straightedge parallel. Keyhole bits in their normal usage require a plunge router, but in this application - you will only need a fixed base router. You will experience rounding on the inside corners - which is unavoidable if this is made from a solid part. Let me caution you, though; 2" x 3" is dangerously small to be routing on. If I were doing this - I would begin with a larger workpiece and cutting the final x & y dimensions would be done last. Your z dimension is determined by your material thickness. Above all, be safe. You don't want to trade a finger for an unfinished part!
*OPG3*


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## Mike (Nov 22, 2004)

Ok, I guess I just do not understand this project. A ridgid piece of Plexiglas will not flex to be inserted into a solid material box this size. Perhaps someone will explain this to me? As I picture this you want a continuous slot around the Plexiglas to retain it. What am I missing?


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## bobj3 (Jan 17, 2006)

Hi Ron

Here's the link for the very small slot cutting bit, it's made to get in the corners of a box ..plus other jobs. note the slot in the white board in the picture..

Box-Slotting Bits - Lee Valley Tools

16J83.02

1/8"

1/8" or 3/16"

1/4"

$30.80
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16J83.12

1/8"

1/4" or 5/16"

1/4"

$30.80

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rpludwig said:


> Bob, on the right track with that t-slot cutter...I'll keep hunting for similar w/bearing.
> 
> Thank you!!!
> 
> Ron


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## bobj3 (Jan 17, 2006)

Hi Mike

I think I know what he wants to do I have done it a time or two.

Clamp the box up without any glue run the bit on the inside of the box then put the Plexiglas in place and glue it up,
You can't see how you got the Plexiglas in place and it's very clean way of doing it, very easy to do on the router table.

It's true you can do it on the router table with drop and slot way and stop blocks with slot cutter or strait bit it's just a fast way to get the job done.

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Mike said:


> Ok, I guess I just do not understand this project. A ridgid piece of Plexiglas will not flex to be inserted into a solid material box this size. Perhaps someone will explain this to me? As I picture this you want a continuous slot around the Plexiglas to retain it. What am I missing?


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## rpludwig (Nov 22, 2011)

OPG3 said:


> I see why some think the transparent parts will be difficult to install, but with only 3- sides - there will be no problem. You can use a keyhole bit without a bearing if you use a straightedge parallel. Keyhole bits in their normal usage require a plunge router, but in this application - you will only need a fixed base router. You will experience rounding on the inside corners - which is unavoidable if this is made from a solid part. Let me caution you, though; 2" x 3" is dangerously small to be routing on. If I were doing this - I would begin with a larger workpiece and cutting the final x & y dimensions would be done last. Your z dimension is determined by your material thickness. Above all, be safe. You don't want to trade a finger for an unfinished part!
> *OPG3*



Otis...thank you again! Your drawing is exactly the concept of the part, the back goes on after the plexi is inserted into the box...and I appreciate the caution, this will be well thought out, b4 attempted, and will be on a larger workpiece...

Ron


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## Mike (Nov 22, 2004)

Ok, after knowing that the PDF is what Ron had in mind I understand.


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