Table saw threaded rod jig

[transatlantic]

There are a few jigs out there that use a threaded rod as an indexing mechanism for the table saw. The ones I have seen are usually American though, and they use an 8Tpi rod, in conjunction with a 1/8" blade. This works out nicely as for one full rotation, the rod advances by the kerf of the blade.

Unless I am mistaken, things aren't quite as convenient with the metric system. It looks like your general ~250mm blade has a kerf of 2.8mm (others I have seen are 2.1, 2.4 and 3.2mm), which doesn't match up with the pitch of any of the larger threaded rods (M16+)

http://fullerfasteners.com/tech/basic-m ... m1-m100-2/

Has anyone done anthing with a threaded rod? if so, what blade kerf and which threaded rod size did you use?

 

[marcros]

american rod is available from cromwell- i got some 1/4x20 unc off the shelf, and it was sensibly priced.

 

[transatlantic]

american rod is available from cromwell- i got some 1/4x20 unc off the shelf, and it was sensibly priced.

That would require you getting an imperial size blade too though, which assuming you could get one that fits, is a little over the top just for a jig?

 

[marcros]

true. I guess that m6 may be useful then- at least one revolution is a useful 1mm. May not be as useful as a kerf width but at least it is a known amount

 

[monkeybiter]

My box joint jig uses an M6 lead screw and a hand-wheel marked with a pencil giving ten graduations, e.g. with your 3.2mm rod you would make 6.4 turns to the next slot. You can also move 6.3 turns [as an example] to make the resulting finger a little narrower, giving an easier fit.
If I was cutting box joints every day [and always using the same TS blade] then I would probably use a leadscrew requiring just one turn, but for occasional use it's no inconvenience.

 

[Bodgers]

is this John Heis' jig? If so that works regardless - I asked him this question a while ago. Mattias Wandel's jig has no such restriction and his plans are in metric.

Another thing to bear in mind - these table saw based jigs work best with a flat top grind blade, particularly if your joint is going to have fingers the width of the kerf. They are harder to come by...there is always the router table...

 

[Brentingby]

A few observations.

3.2 mm is very close to 1/8 inch. Very likely the 3.2mm blade is really 1/8 inch. I haven't measured it to be sure.

From a search for thread pitches, 8 tpi is available on 1 inch dia. rod. Probably a bit heavy for most jigs. More reasonable would be 3/8-16. 16 tpi so 2 turns to get 1/8 in. More easily found, lighter weight and easier on the purse. Or you might find #8 or #10 with 32 tpi.

 

[transatlantic]

is this John Heis' jig? If so that works regardless - I asked him this question a while ago

Not sure how that could be the case? can you explain?

 

[jdeacon]

I did a jig where the threaded rod mostly stayed still, and a half nut on the carriage was moved one or two threads at a time (like John Heisz). And then, unlike John H, to compensate for the mismatch between thread pitch and blade kerf, there is a pointer/handle on the rod to rotate it back and forth for the last cut of a space. The threaded rod doesn't itself move, but rotating it has the effect of slightly modifying the width of the last cut of a space by moving the half nut a little.

So, for example, you:
- cut,
- jump a thread or two,
- cut,
- move the pointer through the necessary angle (100 deg in my case),
- cut,
- reset the pointer back to where it began,
- jump several threads across the finger,
- repeat

 

[Bodgers]

is this John Heis' jig? If so that works regardless - I asked him this question a while ago

Not sure how that could be the case? can you explain?

You replace the rod with your own indexed rod.

He has actually made a video about it recently:

https://youtu.be/0BEl-XAJXIQ

 

[transatlantic]

is this John Heis' jig? If so that works regardless - I asked him this question a while ago

Not sure how that could be the case? can you explain?

You replace the rod with your own indexed rod.

He has actually made a video about it recently:

https://youtu.be/0BEl-XAJXIQ

I saw this video too.

Matches (taken from http://fullerfasteners.com/tech/basic-m ... m1-m100-2/) would be :

2.1mm kerf : 3 increments of an M4 (0.7mm pitch)
2.4mm kerf : 3 increments of an M5 (0.8mm pitch)
2.8mm kerf : 4 increments of an M4 (0.7mm pitch)
3.2mm kerf : 4 increments of an M5 (0.8mm pitch)

It looks as though there is a lot of room for error though (as he mentions himself), and may take a good number of tries to get it right!

To be honest, I think would probably rather keep things simple and use the cranked threaded rod approach.

 

[ScaredyCat]

There are a few jigs out there that use a threaded rod as an indexing mechanism for the table saw. The ones I have seen are usually American though, and they use an 8Tpi rod, in conjunction with a 1/8" blade. This works out nicely as for one full rotation, the rod advances by the kerf of the blade.

Unless I am mistaken, things aren't quite as convenient with the metric system. It looks like your general ~250mm blade has a kerf of 2.8mm (others I have seen are 2.1, 2.4 and 3.2mm), which doesn't match up with the pitch of any of the larger threaded rods (M16+)

http://fullerfasteners.com/tech/basic-m ... m1-m100-2/

Has anyone done anthing with a threaded rod? if so, what blade kerf and which threaded rod size did you use?

I appreciate this is a bit of a necropost but did you ever solve this problem?

.

 

[Deadeye]

I built Matthias' jig using an M8 rod. There are some 3mm kerf blades out there - Freud do some for example. You might need to settle for a slightly smaller diameter than your table saw normally takes.

I added a digital revolution counter to the jig so now I can just put my kerf and desired finger width into excel and print out what stop points to make cuts.

 

[ScaredyCat]

I think I'm going to end up using cogs too. Seems like it should be a simpler solution.

Would be interested to hear of your digital counter..

 

[Alpha-Dave]

I built a box joint jig earlier this year. I used M12 from Toolstation and some coupling nuts with a bent washer between to give a zero-backlash nut. I added a handle on the end to turn the rod. The key to making it accurate is a £40 lathe DRO from ebay. It has 600 mm travel so big enough for any box side I want to make.

https://www.ebay.co.uk/itm/0-600mm-Accu ... 2749.l2649

Just zero it on the first cut and add 3.2 mm for a tight fit or alternatively add 3.2 and 6.4 to give larger fingers. I can use a spreadsheet to give any pattern I want to make it look like a barcode but I don’t know why yet.

I was inspired by a series of videos that used a stepper motor controlled by an arduino and mobile phone but that involved far more electronics and software than I am capable of.

 

[transatlantic]

I appreciate this is a bit of a necropost but did you ever solve this problem?
.

I didn't build anything in the end.

But when I do, I will be using this design instead : https://www.youtube.com/watch?v=5v1QYKWgTvs

 

[ScaredyCat]

I decided that it was probably better to try a different method for this. It's not pretty but we'll call it a prototype for now No glue used on the carriage at all - just screws.

https://www.youtube.com/watch?v=CPFMN1RD8sI

Sorry just a simple upload, no editing, of basic functionality. Wiring is spaghetti at the moment but it works (see below) and I can do different sized fingers. Would like to use a FTG blade to get rid of the 'bat-ears' but I'd need a 200mm one which I can't find anywhere - a bit of a downside on the Draper CTS200 I have - any smaller and the cut height would be about 5mm. Jig was made from scraps. Used m8 threaded rod from Screwfix. Picture of a quick box that I threw together whilst testing and tweaking .

Arduino clone £8
Threaded rod (5 x 1m pack) £10.49 - one rod required
TB6600 motor controller £9.99
Coupler (2 Pack) £5.51 - one required
Nema 23 Stepper Motor £19.99
Micro SD Card Reader (2 pack) £5.99 - one required
Micro Limit Switch (6 pack) £6.66 - 2 required
12v 30a Dc Universal Regulated Switching Power Supply £16

£82.63 - although a little lower if you divide the multipack costs by the units required and not including scraps, glue, screws and 3 LEDs I already had. Most expensive part was the motor, beefy one to move the carriage, then the psu - I guess you could use one out of an old PC.

First real use will be for a small box for the ashes of my little princess who passed away on Friday.