4x non magnetic hold downs

mattbyman · December 7, 2019, 5:54am

Now and then you have material that’s warping. especially when it’s under or up to 1/4" plywood.
I didn’t want to use magnets so I made 4 hold down screws as solution for these thicknesses.

They are designed to work with the crumb tray in place. I just finished making these to be able to continue running jobs. Tomorrow I’ll make better ones that can hold down any thickness with the crumb tray in place.

I used 4x 30mm screws with a 6mm diameter head. Cut off 2 sides of the head so the head of the screw fits through the crumb tray and can be twisted a quarter turn. Then I used 4x small pieces of draft board and screwed 1 screw per piece into them.

There is no sense trying to screw down your material with these hold downs. You’re better of wedging another piece of draft board under the hold downs.
I hope you can use these hold downs

Cheers

Jules · December 7, 2019, 6:00am

Looks like a clever solution to the warping problem.

mattbyman · December 7, 2019, 6:01am

Thanks Buddy

Basically not just for warping. Also for holding down material for any job

evansd2 · December 7, 2019, 10:43am

I’d be careful how much torque you apply to the honeycomb. It’s strong but not bulletproof, the last thing you want is to bend it.

mattbyman · December 7, 2019, 6:58pm

I appreciate your concern.
Logic tells me I don’t need torque to hold down plywood and such.

With all respect, it’s in the name isn’t it?
Hold down, not, Bolt down

cheers

evansd2 · December 8, 2019, 3:29am

1/4” plywood like you mentioned can warp a good bit and would sometimes require a fair bit of torque to crank down.

I’ve never done any kind of testing to know just how strong the honeycomb is. As you say logic would dictate that it’s pretty strong, but I’m not going to test it for the sake of a janky piece of plywood.

mattbyman · December 8, 2019, 4:00am

Hi,

Yes your right. It can require a fair bit of force. Thats why I don’t trust magnets to do the job.

Besides that, there is a limit to how much of warped plywood one desperately wants to cut and how big you need the cutout to be.

I mean, holding down is one thing but as soon as one takes her/his job out it’s still going to warp.

So, there is a limit of allowable warp. It’s up to the operator, right?

Simple rule of thumb would be: Material needs a hold down torque? Might as well cut with a fork.

Cheers

randy.cohen · December 8, 2019, 4:02am

You should use Nylon screws instead of steel. The Nylon will be “sacrificial” and you’ll have to replace them periodically as they wear out, but they won’t do any damage whatsoever to the crumb tray…

mattbyman · December 8, 2019, 4:21am

I bought longer brass bolts 8-32 × 1" 1/2 and 2" with 8-32 x 1/8"nuts.

I’m afraid nylon will eventually get pulled into the honeycomb, sheer off or deform and get slop or play.

ChristyM · December 8, 2019, 4:43pm

Were the honeycomb hold down pins not working for you? Just curious about use case.

mattbyman · December 8, 2019, 5:03pm

If you mean the pins you can cut then, no.
Those loose their bite over time from.

markevans36301 · December 8, 2019, 5:14pm

They do but you can make a dozen from a small piece of scrap so I have a quart or so of them at any one time. One gets loose I just chuck it in the trash and grab another one.

Jules · December 8, 2019, 5:32pm

Chuckle, me too! I find them everywhere in the office! (And they seem to make a seasonal migration to the kitchen too.)

ChristyM · December 8, 2019, 5:48pm

Gotcha. I think I tend to lose them (or my cats steal them) before that happens!

mattbyman · December 8, 2019, 6:43pm

Sure, what ever is clever. I just need a permanent hold down solution and not having to think about a pin loosing it’s bite close to the end of a fairly long job.

markevans36301 · December 8, 2019, 7:05pm

I’ve never had one pop up during use but if this is a concern maybe this is better for your use case.

Also I’m not against adding arrows to my quiver. Would you mind doing a photo of this in use? I’m not sure I am getting how you use it.

mattbyman · December 8, 2019, 7:32pm

Sure no problem. I’ll try to make a detailed work process step by step and post it here.

For me, comming out of the machine shop sector business, the process of making these is fun.

Cheers

mattbyman · December 10, 2019, 5:45am

Hi markevans36301,

In all it turned out differently than what I had planned but this works great too.

What I used is a 6-32 threaded insert combined with a 1" long bolt X12 and 2 component glue.

I opened the crumb tray (removed the alu backing)

Figured out a pattern to place the inserts. (9 along the edge and 3 in the middle)

Pulled the inserts up to the honeycomb with the 6-32 bolt. This way it’s tight to the honeycomb but not yet in.

Applied the glue to the inserts and pulled them into the bottom side of the honeycomb and let it sit for a while.

I also made custom walnut clamps.

It’s up to you if you want to install washers on the bolts to make sure your not screwing them in to the topside.

Personally I did not use washers because if you allow just the head of the screw to enter the honeycomb you end up with a clear indication as to where to insert a hold down.

This is just for the occasions when you need a good hold down compared to the bite of the wooden hold down pins. Never the less, Pins will surely stay in the work flow.

If you have questions, just shoot.