Shaper hold down clamps

[Mitch schiffer]

I'm looking for a upgrade to my sliding table shaper hold downs. I will be cutting extended tenons and don't trust my current set up. I see some pneumatic hold downs on Amazon. Has anyone ever tried those or if there a better option? I attached a picture of my current set up and the Amazon clamps.
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[Jared Sankovich]

I like pneumatic cylinders personally. They are cheap, easy to configure, effective as clamps and versatile.

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[Greg Quenneville]

Airtight clamps seem to be the best, most expensive around. Popular with the Felder owners. You can find single action cylinders on the auction site and fabricate up a holder, but it becomes an involved process with air supply etc.

Bimba cylinders seem the most common in the 174 size, but you could likely use the shorter 172 or 173. Bimba cylinders have an odd sized rod, so you will need an adapter for whatever foot you use. Luckily you have McMaster Carr for all the parts you would need.

I am fabricating a set of clamps for my slider right now, including a thruster for lateral clamping to the fence extrusion. It gets spendy quickly if you use stainless and fancy hardware for the holders. I think I have > $800 invested in all the parts.

Greg

[Mitch schiffer]

I like pneumatic cylinders personally. They are cheap, easy to configure, effective as clamps and versatile.

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How are these mounted? Do they have a flange on them?

[Jared Sankovich]

How are these mounted? Do they have a flange on them?

They are nose mount cylinders. Though there are other configurations.

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[Mitch schiffer]

They are nose mount cylinders. Though there are other configurations.

Thanks. I ordered a couple similar cylinders off ebay that im hoping will work. Do you ever find the hose to be in the way?

[Warren Lake]

How much travel do you need. They make shorter air cylinders.

[Mitch schiffer]

I'm thinking 2" then I can use the same set up for 3/4 stock up to 2 1/4 stock and still have 1/2" to get the thicker stock in place.

[Warren Lake]

thats sensible for up to 2 1/4" doors. Old guy said he did doors in 2 1/4 and 3 3/8 then the thick church stuff. I need to go to city hall sometime and see if his doors are still on there and if so what they are.

Im not sure the travel on my shorter ones on two machines but will try and measure that tomorrow. I think it wont be enough. Air for them is simple with a toggle switch but past i used to take the clamps off my Blum machine and used a floor foot pedal.

[Bobby Robbinett]

Are you talking about something like a pneumatic cope or tenon sled? Grizzly, and Weaver both make nice ones. I have a Ritter pneumatic sled made out of 1” thick aluminum. Lots of ways to do this. I have even seen one shop take a Weaver sled that rode in the miter track and put a long pneumatic cylinder on the back side activated by a foot pedal that would push the sled through the shaper cut and then pull it back out. Pretty neat way to do it.

[Mitch schiffer]

Are you talking about something like a pneumatic cope or tenon sled? Grizzly, and Weaver both make nice ones. I have a Ritter pneumatic sled made out of 1” thick aluminum. Lots of ways to do this. I have even seen one shop take a Weaver sled that rode in the miter track and put a long pneumatic cylinder on the back side activated by a foot pedal that would push the sled through the shaper cut and then pull it back out. Pretty neat way to do it.

My shaper has a sliding table so I don't need a sled. Just a better way to hold down stock.

[Mitch schiffer]

Ok I have an update on this I came up with a different hold down but it has its own issues. There is too much deflection in the cylinder rod to hold a workpiece securely. If I crank up the air pressure then my mount has deflection. Any ideas on how to improve this?

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[Kevin Jenness]

The clamps need to be mounted independent of the fence. The central post of the miter gauge might be stout enough, or you can use other tapped holes in the table to mount brackets. Cam clamps I have used typically have a vertical post with a height-adjustable bracket in which slides a horizontal beam with the clamp at the end, allowing a fair amount of adjustability to get the pressure where needed. Your setup will not do a lot to hold down the far edge of a wide rail. For the narrow part shown you would need to double it up to keep the clamp foot from tilting.

You will want a backer strip (maybe that is what you are showing) to suppress spelching as the cutter exits the workpiece. Most people screw the backer through the fence. I have found that a fresh backer at every cut works best so I use loose backers and clamp the workpiece and backer horizontally to the fence with some sandpaper glued to the fence. to ensure the backer doesn't get loose.

[Mel Fulks]

You could make wooden “fingers”. Angled board with saw cuts making each about 3/16ths wide. Clamp to fence.

Or use screws if you use a wooden fence

[Mitch schiffer]

I'm not getting any defection of the miter gauge but more of the bracket that I made and the rod of the cylinders. This shaper came with a cam clamp that was mounted to the post on the miter gauge. I never liked that one. It was difficult to adjust to work correctly.

[Jared Sankovich]

Ok I have an update on this I came up with a different hold down but it has its own issues. There is too much deflection in the cylinder rod to hold a workpiece securely. If I crank up the air pressure then my mount has deflection. Any ideas on how to improve this?

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What bore and shaft size are those? That mount needs to be heavier to keep it from deflecting.

[Kevin Jenness]

If you feel the fence is sturdy enough to mount the clamps to then use heavier gauge material for the bracket. That fence extrusion looks a bit light for the purpose but you are in a better position to judge. What pressure are you feeding to the clamps? If the rods are deflecting they may be defective or not suited for the task. They need to remain vertical or tipped toward the fence in use to keep the material from creeping forward away from the fence and backer.

[Bill Dufour]

Seems like a flange mount cylinder would be easy to mount. Or they make flanges that can be attached to a tie rod cylinder.
Bill D

[Jared Sankovich]

1.5" is the minimum bore I'd be comfortable with, ideally it would be 2" with a 5/8 rod.

[Warren Lake]

the big shops often had a guy who built custom stuff and modified machines to make a process work better and faster. This rig was built to do cathedral raised panels with a very large cutter in one pass. Your set up is not up to the job.

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[Bill Dufour]

Warren what is the flat sheet on that rig? Aluminum die plate would be my guess.
Bill D.

[Warren Lake]

1/2" plate steel. Also very interesting is custom guy built this with an outboard bearing. A template went in below and allowed it to follow the bearing but from the outside not at the cutter head. As well there was precision guides below and an air piston so you could run air pressure to maintain bearing contact and not have to focus on doing that when machining, you pick how much you want. Had Thompson linear bearings below I thnk was the brand.

[Michael Schuch]

Another possibility to consider:

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https://www.amazon.com/Kreg-KBC3-BAS-Bench-Clamp-Base/dp/B0774X67G8/ref=sr_1_6?crid=2VOPPWWXZFYA7&keywords=kreg+hold+down+clamps&qid=1652143192&sprefix=kreg+hold+down+clamps%2Caps%2C201&sr=8-6

When I have experimented with pneumatic clamping in the past I have found that I do not use it enough to make it worth the hassle FOR ME. I found that I prefer mechanical hold down clamps for most things due to there simplicity. If I were a production shop pneumatic clamping would probably have much more appeal to me.

[Bill Dufour]

1/2" steel plate. I bet that was not lifted off very much.
bill D

[Warren Lake]

Dedicated machine. Seen up to 12 shapers in a shop so same thinking. The THK bearings or whatever Thompson maybe were screwed right into the top of the shaper table then all this rode on that but also on other bearings under this so it went in and out as well as front to back, that allowed curved work. Yes it was heavy when I took it off the machine. No negatives about the weight, their focus was getting the work done and heavier is better.

[Mitch schiffer]

They are 1 1/16 bore, 3 inch stroke, I believe the rod is 5/16 possibly 3/8. I did look for a extrusion that I could stack on top of the existing one however it was a odd size and the t track is not centered. That is how I ended up with the mount I have. Im now wondering if there is a simple way to use the vertical post but put a larger cylinder on that to add to my current set up. I do believe this set up is sufficient for cabinet door but I don't think it will be for larger projects.

[Jared Sankovich]

They are 1 1/16 bore, 3 inch stroke, I believe the rod is 5/16 possibly 3/8. I did look for a extrusion that I could stack on top of the existing one however it was a odd size and the t track is not centered. That is how I ended up with the mount I have. Im now wondering if there is a simple way to use the vertical post but put a larger cylinder on that to add to my current set up. I do believe this set up is sufficient for cabinet door but I don't think it will be for larger projects.

Your cylinder bore is too small for effective clamping. A 1.0625 bore is only .89 sq inches. Assuming you are running 100 psi that's only 89 pounds of force per cylinder. To compare I'm running 211lbs of force per cylinder on my sled.