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-   -   Pocket Holes (http://www.mechmate.com/forums/showthread.php?t=2141)

sailfl Fri 18 September 2009 09:10

Pocket Holes
 
Is there anyone that might be interested in seeing a macro that would create Pocket Holes like those made by a "Kreg Jig". I am thinking of creating one and I would like some input or ideas. If you use a Kreg Jig, I would like to hear from you also.

Thanks

inventall Fri 18 September 2009 09:36

I use a kreg jig. Love it, can’t live without it. This link talks about doing pockets on a shopbot. http://www.shopbottools.com/garysmusings.htm#Jig[/URL]

sailfl Fri 18 September 2009 09:42

Pete,

I know about the shopbot link but thanks.

bolingerbe Fri 18 September 2009 09:52

Very Interested
 
I have a kreg jig and used it a lot when I was constructing cabinets. As I am trying to get back into the swing of things and about 1/2 with my MechMate, I am very interested in this. At present I do not know how much help I would be, but I have a lot of interest.

inventall Fri 18 September 2009 10:23

Just thinking about It, The kreg jig is so fast to use and works great that I am not sure if it is worth doing on the MM. If I could get my MM to tie my shoes I probably would:D. But the MM is not going to drill the pilot hole for the screws and on material like MDF you need the pilot so it does not blowout. With out the pilot you will have to take a lot more care installing the screws the angle has to be perfect.

domino11 Fri 18 September 2009 10:31

I wondered about the pilot hole as well. I have seen some cabinet software that stated they can do pockets on the cnc. With the sheet flat you would only get the pocket with no pilot hole. I assumed you would have to manually drill the pilot hole. Has anyone, maybe Mike R, done this for cabinet work on a cnc?

bradm Fri 18 September 2009 10:57

GCode Subroutine for Pocket Holes
 
Nils and I have been having an offline chat about handwritten gcode. There's a rather nice example using EMC2's conditional and looping constructs.

Nils mentioned an interest in pocket holes. Since both EMC2 and Mach3 support subroutines and parameters, here's a gcode fragment illustrating how it might be done.

This code fragment assumes that the pocket slot is not wider than 2x the cutting bit diameter, and that the full depth can be cut.

Should work equally fine in MM if you fill it your own numbers.

This is untested as of yet, just written off the top of my head:

Code:
#40 = 0.25   (Bit diameter)
#41 = 0.375 (Pocket slot width)
#42 = 0.625 (Deepest slot point)
#43 = 2.0 (Pocket slot length)
#44 = 0.5 (Pocket slot set back from edge)
#45 = 0.1 (Safe height)
#46 = 0.0 (Top of material height)
#47 = 75 (Plunge Speed)
#48 = 150 (Cut Speed)

O5001 SUB (Cut a pocket slot along the Y axis increasing based at P1,P2)
G00 Z[#45] (Raise to safe height)
G00 X[#1-#41/2+#40/2] Y[#2+#44]  (Rapid to location, offsetting)
G01 Z[#46-#42] F[#47]  (Plunge to full depth)
G01 Y[#2+#44+#43] Z[#46] F[#48]  (Cut ramp upward)
G01 X[#1+#41/2-#40/2]   (Across to other edge offset)
G01 Y[#2+#44] Z[#46-#42]  (Cut ramp downward)
G00 Z[#45] (Back out to safe height)
O5001 ENDSUB

O5001 CALL [3] [0]   (Pocket hole 3" in along edge of a board at 0,0)
O5001 CALL [9] [0]   (Pocket hole 9" in along edge of a board at 0,0)
A smarter variant of this might take two more parameters, X slot direction and Y slot direction so that you could call it like this, and avoid needing four separate subroutines:

Code:
O5000 CALL [3] [0] [0] [1]  (Pocket hole 3 inches in, Y increasing)
O5000 CALL [9] [0] [0] [1]  (Pocket hole 9 inches in, Y increasing)
O5000 CALL [12] [2] [-1] [0]  (Pocket hole 2 inches in, X decreasing)
O5000 CALL [12] [8] [-1] [0]  (Pocket hole 8 inches in, X decreasing)
O5000 CALL [9] [10] [0] [-1]  (Pocket hole 9 inches in, Y decreasing)
O5000 CALL [3] [10] [0] [-1]  (Pocket hole 3 inches in, Y decreasing)
O5000 CALL [0] [8] [-1] [0]  (Pocket hole 2 inches in, X increasing)
O5000 CALL [0] [2] [-1] [0]  (Pocket hole 8 inches in, X increasing)

(This needs math something like this:)
#50 = [#41/2-#40/2] (Offset is 1/2 slot width less 1/2 bit width)
G0 X[#1 + #44*#3 - #50*#4]  Y[#2 + #44*#4 - #50*#3]  (Rapid to location, offsetting)
I suppose a fully generalized version using trig functions is possible as well, but seems like overkill.

Richards Fri 18 September 2009 11:31

The pilot hole is the problem. I've cut the tapered "slots" on my CNC, but without a pilot hole, the results were very disappointing.

I have both the old style metal Kreg Jig and the newer blue plastic Kreg Jig. They work very well. Although they take up space and require that I manually handle large parts, because they have a pilot hole, they work better than my attempted CNC program.

domino11 Fri 18 September 2009 11:48

Thanks for the input Mike. Have you tried the manual pilot hole drilling afterward? Probably just as much work as doing the pocket holes manually.

Richards Fri 18 September 2009 15:04

With the Kreg jig and drill, making a hole is both easy and quick. I think that it would take more time to align the drill to make that pilot hole than it would have taken to use the Kreg jig in the first place.

smreish Fri 18 September 2009 15:17

I love my KREG tool. Best 100 bucks I ever spent!

Gerald D Fri 18 September 2009 21:31

What is a "pocket hole"?

inventall Fri 18 September 2009 22:14

3 Attachment(s)
Sorry, pictures should help.

Gerald D Fri 18 September 2009 22:58

Thanks.

I am assuming that you are not going to align the router with the screw axis?

inventall Fri 18 September 2009 23:09

No I don't think so. I think there looking to do this:

Sorry Pete, ShopBot has the copyright on the pictures that are now deleted from here.

sailfl Fri 18 September 2009 23:54

Yes, they would look like the photos that looks like they came from Gary's CNC Musings ShopBot site.

http://www.kregtool.com/products/pht/index.php

The tool comes with a bit that creates the pockets but also drills a pilot hole for the screw. That is what others are refering to. What they have not mentioned is that the screws are self taping. The system is very popular because it does a fantastic job of attaching boards and many cabinet makers are using them. The system works with different thickness of material.

Gerald D Sat 19 September 2009 00:36

I think that you could avoid the pilot hole to some extent if you use screws with thin, smooth shanks. Or, put in another way, your screw selection is an important consideration before discussing pilot holes.

sailfl Sat 19 September 2009 00:45

Gerald,

Kreg Tools have their own screws that are self taping and work with the system but can be bought separately.

http://www.kregtool.com/products/spp/index.php

They even say that their screws will not split the wood if they do not have a pilot hole.

I respect the input of the members that would rather have the pilot hole which does make driving the screws easier but if you have lots of boards to do, you can save a lot of time if you do not have to use the jig.

The Kreg Jig is so popular here, I am surprised they are not selling it in the foreign markets.

I will add a photo later today of one pocket hole that I have cut.

Jan de Ruyter Sat 19 September 2009 00:48

I have been using a Lamello biscuit machine (there are many other makes) for many years to do the same operation for frame-less cabinets. A good glue provides a strong joint. Stuff that I made 20 years ago still stands.

The advantage of using a biscuit machine is the ability to cut precise grooves so that the alignment of the sides becomes a trivial matter while creating an invisible joint. No special clamping tools are required, except a flat surface. A stop at one side of the table helps when doing the uprights. On assembly, glue and biscuits are inserted into the grooves and the carcass is clamped with sash clamps. The fronts of the sides and shelves are aligned with a little tap from a tool: persuasion to produce a strong, sturdy cabinet.

Before the Lamello, I used an overhead router to cut a tongue-and-groove joint, but the problem was always the edging on the front of the side and shelves.

When making a carcass frame, I used a tongue and groove joint to join the rails and stiles, but it is time consuming to set up properly. A 45 deg joined with a biscuit provides a neat joint, but not as strong, but if you glue and nail the frame to the cabinet sides, this becomes a non-issue.

sailfl Sat 19 September 2009 00:57

Jan,

Joining wood with biscuits is popular also. It works well if you don't want to have a pilot hole showing. The advantage that the pocket screws have over the biscuits is that you don't need clamps or once you have used pocket screws you can immediately remove the clamps. When you use biscuits, you want the glue to dry before removing the clamp. You can work faster with pocket screws. Both are excellent ways to attach two pieces of wood and both have there use.

Alan_c Sat 19 September 2009 04:21

1 Attachment(s)
I am the local agent for Kreg tools in Cape Town.

The pilot holes they refer to as not being necessary are the ones in the wood that has not been drilled (ie the piece you are screwing onto, not the one with the pocket) You have to have the clearance hole in the bottom of the pocket or you may get jacking while trying to screw the two pieces together. MDF will most definetly split if you try and drive the pocket screw through the bottom of the hole without the clearance hole.

The screws for the pocket hole system irrespective of the manufacturer are very specific in that they are flat bottomed with mushroom type heads. Countrsunk screws will not work as the timber will split due to the wedging action of the cone. The manufacturers also make two different thread types to suit hardwood (fine) or softwood and man made boards (coarse). Certain types of sheetmetal self tapping screws may work but the thread choices are more limited. The correct screws are a bit more expensive than standard wood or chipboard screws but the versatility and strength of the system far outweighs any cost difference.

Attachment 6205

sailfl Sat 19 September 2009 07:06

1 Attachment(s)
This is a pocket hole I cut in one pass using a .25" end mill in MDF.

hennie Sun 20 September 2009 02:59

Alan what is the cost of such a jig?Like Jan I also use a Lamello and sometimes I use the multi borer mostly to make butcher tables.

Robert M Sun 20 September 2009 04:56

Hennie,
Her's the link to the Kreg Tool Co, maker of this jig & all sorts of other aid-shop tools w/prices.
Have fun discovering it & happy navigation ;)

Alan_c Sun 20 September 2009 06:20

Hennie

Price for the K3 master system is about R1700.00 inc vat, excl postage. contact me off list and I will get you up to date pricing (depending on exchange rate) Local site

inventall Sun 20 September 2009 07:23

I will sometimes use a biscuit jointer with the pocket holes. The biscuits keep it in line and the screws clamp the glued joint.


p.s. Sorry about the pic's in post 15,I didn't know

hennie Sun 20 September 2009 07:46

Alan how would it work for melamine drawer boxes ,would it be strong to do a melamine drawer with the pocket hole compared to putting a chip board screw through the side of the melamine and the speed at manufacturing.

sailfl Sun 20 September 2009 08:02

Hennie,

I believe it works with most wood materials.

Alan_c Sun 20 September 2009 09:53

Works great for drawer boxes, it also makes it look neater as there are no screw heads visible once the draw front is attached. Strength is good and is useable for many different applications (attaching lipping is one thing in particular you would use regularly)

smreish Sun 20 September 2009 12:13

I use the Kreg system pretty exclusively for all furniture construction. As noted, I often will use a biscuit in the joint line to keep things lined up. The best part is there is no "glue" time to worry about. I build raised panel doors all the time without the need for bar clamps or dry time. The local Lowe's sells the system for about 110 dollars.


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