Bench Dogs for Jet Parallel Jaw Clamps - Suitable for MFT?

[Forrest Anderson]

It seems that Jet sell bench dogs that fit into the base of their parallel clamps, and the other end of these dogs then fit into holes in a workbench. The dogs stop the clamps from falling over, and if the holes are arranged in a grid, it means that the clamps are nice and parallel or square to each other.

The clamps are reviewed athttp://www.newwoodworker.com/reviews/jetclmprvu.html and there is an accompanying video which shows the dogs being used in conjunction with a board which has a few holes drilled into it. The following stills are taken from that video, and show what I'm talking about:

It strikes me that these bench dogs would be great when used in conjunction with an MFT, even though the dogs are apparently 23/32" in diameter (18.3mm), and the MFT holes are slightly larger at 19.8mm. A few turns of some insulating tape around the dogs would make them a nice snug fit though.

Has anyone tried this combination?

Forrest

 

[Brice Burrell]

  Forrest, I finally got around to buying some parallel jaw clamps last week, I went with Jet. You could use the MFT, but the holes are a little too big as you pointed out. I don't know if this is big deal or not, I've not tried it yet. Jet also has what they call framing blocks (or something like that) they hold the two clamps at a right angle to each other, this seems to be a better system. I bought the clamps in sets with the framing blocks. When I get a chance I'll try it both ways and let you know.

 

[Forrest Anderson]

  Forrest, I finally got around to buying some parallel jaw clamps last week, I went with Jet. You could use the MFT, but the holes are a little too big as you pointed out. I don't know if this is big deal or not, I've not tried it yet. Jet also has what they call framing blocks (or something like that) they hold the two clamps at a right angle to each other, this seems to be a better system. I bought the clamps in sets with the framing blocks. When I get a chance I'll try it both ways and let you know.

Brice

I look forward to hearing how you get on, although sadly it seems that the Jet clamps are not available here in the UK.

If you check out the video I mentioned, the author of the review screws the bench dogs into the bottom of the Cross Doc Framing Blocks. By doing this, he gets squareness from the dogs sitting in holes in the worktop and from the clamps sitting in criss-cross notches in the Framing Blocks, which gives the best of both worlds.

Forrest

 

[Eli]

Bessey has similar cross blocks as well.

 

[enderw88]

It looks like it would be simple to remove the bench dogs and replace them with the 1/2 inch(?) couplers that Jerry Work (I think) mentioned would fit through the MFT holes.

 

[Brice Burrell]

Craig, the dogs thread into the Jet clamps and cross blocks, take a close look at Forrest first pic. I thought about drilling 3/4" holes in my MFT in between the 20mm holes.

 

[TahoeTwoBears]

I bought what is probably the same set from Amazon the other day. The benchdogs are small, but I noticed that they're threaded 1/4 x 28. Seems like it might not be too hard to replicate them in some manner for a perfect fit.

Mike

 

[enderw88]

Craig, the dogs thread into the Jet clamps and cross blocks, take a close look at Forrest first pic. I thought about drilling 3/4" holes in my MFT in between the 20mm holes.

Yeah, I wasn't too clear. use some threaded rod to attach the couplers to the clamps.  What thread does the clamp take?

 

[Ned]

...I thought about drilling 3/4" holes in my MFT in between the 20mm holes.

Argh!  But you dismissed it, because it would be wrong, right?  Drilling additional, only very slightly different holes in the MFT top makes me cringe. 

The bench dogs are sold separately.  Make or have made some 20mm ones.  Neither clamp nor MFT top hacked, compatiblity perfect.

Ned

 

[TahoeTwoBears]

Ned, I agree about just fitting the 20mm bits. Any idea where you can obtain them? I'm thinking that it would be easy to simply get the proper length 1/4 x 28 bolt and put it through a 20mm sleeve. Should thread right in to the Jet clamp's system.

 

[HowardH]

FWIW, I have that Jet set and the bessey and these Jet's are clearly superior clamps.  The heads a lot larger and even more important, the moving jaws don't fall when you hang them up.  I'll be getting more of them.  They're great!

 

[Ned]

Ned, I agree about just fitting the 20mm bits. Any idea where you can obtain them?

McMaster will sell you a 1m length of 20mm Al for ~USD40.  Probably anyone else would be cheaper.

Just about any metalworking lathe could make short work of converting inch-dimensioned (much cheaper) stock to 20mm.

I'm thinking that it would be easy to simply get the proper length 1/4 x 28 bolt and put it through a 20mm sleeve. Should thread right in to the Jet clamp's system.

Are you sure about the 1/4x28?  Sure it isn't metric?

Dogs made for the MFT don't have to be 2 inches long.

The bottom end of the dog could be tapped M8x1.25 to fit the Festool knobs (as used on the Angle Stop and the Clamping Elements).

Ned

 

[Steveo48]

FWIW, I have that Jet set and the bessey and these Jet's are clearly superior clamps.  The heads a lot larger and even more important, the moving jaws don't fall when you hang them up.  I'll be getting more of them.  They're great!

Every review that I've read comparing Bessy and Jet parallel clamps is just as Howard says.  I bought the 2 x 24" & 42" Jet clamp set in October and love them, they are far, far better than the iron clamps that I've been using.  The set is avaialble at Amazon (best price I could find) and included the two dogs and clamp blocks.

I made a simple stand that I screwed into my bench that accepts the dogs, it's really great not to have to fight them falling over now.

Steve

 

[cdconey]

Couldn't you just wrap the dogs with masking tape to make them fit tighter in the 20mm hole?

 

[TahoeTwoBears]

Okay, I fiddled around with the Jet set a bit yesterday. It's true that the bench dogs area sloppy fit, but in truth it probably doesn't matter much as long as you square the piece you're working on. However, I'm a bit more fussy than that, so I've been trying to come up with a better design that would be easy to implement. A machinist friend of mine stopped by last night and we discussed the problem. He came up with a much more elegant solution (at least we're hoping so). He's going to play around with machining some "plastic sleeves" that will just fit over the dogs. He intends to machine them to tolerances that will require me to freeze the dogs for a couple of hours and then press them on. He wants to play with it over the weekend to make sure that any expansion of the sleeve (from heat) won't bind up in the 20 mm holes, but remains a snug fit.

The beauty of this is that it won't require messing around with different threads, etc. It appears that the dogs (which are two part) are nice in yet another way. If you want to affix the clamps to the bench more solidly, then simply screw on the short dog to the clamp, insert it into the table, and then place a 1/4" fender washer under the table when you screw on the next part of the dog (then extension). Seems to work well.

I'll let you know how the sleeves work out and post the dimensions later if anyone's interested.

Mike

 

[ohkipp]

You guys have me really scared...  I took out the dogs, replaces them with a bolt, slid the bolt into the front and rear tracks, end of story.
It really seemed like the best solution and I use it every day.

 

[bdormer]

The posts on the Jet clamps have some slop in the fit with 3/4" dog holes - So I wouldn't think that a loose fit on an MFT (or anything else drilled with 20mm dog holes) would be a problem.

 

[Hergy]

Can anybody verify that the threads on the Jet are truly 1/4-28?  Seems odd as it would be my guess that they are metric. 1/4-28 is one size of bolt/nut that I have never used, so I don't have any around to try out. If all else fails, it's off to Ace Hdw to verify. Every time I go to Ace, I get lost back in the fastener section with all the little plastic boxes. I swear I always find something new (like an elevator bolt!).

 

[Dave Ronyak]

...I thought about drilling 3/4" holes in my MFT in between the 20mm holes.

Argh!  But you dismissed it, because it would be wrong, right?  Drilling additional, only very slightly different holes in the MFT top makes me cringe. 

The bench dogs are sold separately.  Make or have made some 20mm ones.  Neither clamp nor MFT top hacked, compatiblity perfect.

Ned

Brice and Ned,

The dogs simply hold the Jet Clamps in position, right?  The dogs are not loaded when the parallel jaws move to clamp up your project, right?  If the foregoing is correct, then dogs made by cutting/turning and internally threading pieces of hardwood dowels should work.  The pieces can be sanding to needed OD size to fit MFT holes.  I've been successful internally threading hard maple in the past using standard metal threading taps.  I have several pairs of Bessey Clamps and a few branded Scott Phillips, so Jet bar clamps aren't in my budget plan unless they appear at close out prices.

Dave R.

 

[Les]

Threads on my dogs are M6.