a quick holdfast question

[bridger berdel]

My main workbench has a top made of one sheet of 3/4" mdf topped with 1 sheet 3/4" melamine board. It's a good work surface in a number of ways, but not ideal for holdfasts. Between the material being crumbly and the slick surface requiring that the holdfast be perhaps tighter than in some other materials i expect the lifetime of the holes to be short. I drilled it at 7/8" and dropped a holdfast in and it worked, but i can see that the holes will deform pretty rapidly.

Anyone know of a solution here?

[Jim Koepke]

Would it be possible to insert a thick piece of hardwood in the places where you want a holdfast and then drill it for the holdfast?

This may require drilling or cutting out a large area and using a piece that is stepped so there is a larger area under the top.

jtk

[ken hatch]

My main workbench has a top made of one sheet of 3/4" mdf topped with 1 sheet 3/4" melamine board. It's a good work surface in a number of ways, but not ideal for holdfasts. Between the material being crumbly and the slick surface requiring that the holdfast be perhaps tighter than in some other materials i expect the lifetime of the holes to be short. I drilled it at 7/8" and dropped a holdfast in and it worked, but i can see that the holes will deform pretty rapidly.

Anyone know of a solution here?

Bridger,

It's been about six months since the last bench was finished, I could be talked into building another pretty easily, especially if I had some help :D.

ken

[bridger berdel]

Hmmmm.... i could see something like a floor flange with a pipe tap run in from the other side to reverse the taper of the threads, with a stub of pvc pipe threaded in that way, mounted to the bottom of the benchtop and trimmed flush. Hey, it might work. The pvc might be too slippery or dense or brittle for the holdfast to grab well, or there might be another plastic that would be better.


Anyone have data about the length/diameter parameters for holdfast holes?


Thoughts?

[Jim Koepke]

Hmmmm.... i could see something like a floor flange with a pipe tap run in from the other side to reverse the taper of the threads, with a stub of pvc pipe threaded in that way, mounted to the bottom of the benchtop and trimmed flush. Hey, it might work. The pvc might be too slippery or dense or brittle for the holdfast to grab well, or there might be another plastic that would be better.


Anyone have data about the length/diameter parameters for holdfast holes?


Thoughts?

My idea was for hardwood. As far as using plastic, you may be right about it being too slippery.

jtk

[bridger berdel]

My idea was for hardwood. As far as using plastic, you may be right about it being too slippery.

jtk

I don't want to have to cut out a large section to insert hardwood. It's a melamine top, for better or for worse and making *part* of it wood seems like i'd end up with a worst-of-both-worlds situation.

[David Eisenhauer]

I added a construction grade strip of 2 x material to the underneath side of my first workbench where I was going to drill out holdfast holes. 1" of ply+beaver board plus 1-1/2" of SYP worked well with the TFWW holdfasts.

[bridger berdel]

I added a construction grade strip of 2 x material to the underneath side of my first workbench where I was going to drill out holdfast holes. 1" of ply+beaver board plus 1-1/2" of SYP worked well with the TFWW holdfasts.

So 2-1/2" thick with ply on top and syp on the bottom?

[Alan Schwabacher]

I would just use it, and if the holes get deformed to the point the holdfast slips, I would first try lining the hole with construction adhesive. If that fails, you can always drill it out and put in a hardwood liner.

[William Fretwell]

Your bench top is 1 1/2” thick, holdfasts prefer 2 1/2 to 3 1/2”. Where you want the holes I would add more wood. Lining the holes with epoxy will extend their life.

[Jim Koepke]

Your bench top is 1 1/2” thick, holdfasts prefer 2 1/2 to 3 1/2”. Where you want the holes I would add more wood. Lining the holes with epoxy will extend their life.

My saw benches are made with construction 2X material that is 1-1/2" thick. They grab a holdfast just fine. Thicker is going to be better up to a point. When it gets too thick the holdfast doesn't have enough of an angle to cause it to hold by jamming with the wood.

It can also depend on the texture of the shaft on the holdfast. A rough texture will hold better than a slick shaft.

jtk

[michael langman]

I read somewhere where someone used either 3/4 or 1" copper pipe. He drilled holes in his bench for a tight fit on the diameter of the copper pipe and the holdfast fit very well to the inside diameter of the pipe. I was going to do it with my pine bench but decided to wait till the holes wore out.

[David Eisenhauer]

1/4" hardboard - 3/4" ply - 1-1/2" SYP. The bench was turned upside down and the SYP was glued/screwed to the bare plywood of the underneath side of the workbench top. The holdfasts from TFWW worked well, but the hardboard top of the workbench made things slippery. Added suede leather to the faces of the holdfasts for better holding. Worked well until I built a typical Ruobo style workbench.

[Frank Martin]

My bench top is made from 4 layers of plywood topped with 1/4” masonite. I drilled holes and lined them up with 3/4” copper pipe that is glued with gorilla glue to the ply layers. Served me well in the last nearly 15 years using Veritas hold downs.

[bridger berdel]

My bench top is made from 4 layers of plywood topped with 1/4” masonite. I drilled holes and lined them up with 3/4” copper pipe that is glued with gorilla glue to the ply layers. Served me well in the last nearly 15 years using Veritas hold downs.

Can you post a link to the hold downs you use please?

[Frank Martin]

Can you post a link to the hold downs you use please?
Here it is:

http://www.leevalley.com/us/wood/page.aspx?p=31149&cat=1,41637

I don’t have any experience with other hold fasts, but these worked perfectly for me. One thing I really like about these is that there is no need to whack them with a hammer and pressure easily adjusted using the brass knob.

[bridger berdel]

Here it is:

http://www.leevalley.com/us/wood/page.aspx?p=31149&cat=1,41637

I don’t have any experience with other hold fasts, but these worked perfectly for me. One thing I really like about these is that there is no need to whack them with a hammer and pressure easily adjusted using the brass knob.

Thanks. Lining the hole with copper pipe is an interesting option.

[Karl Andersson]

Woden and Record (at least) made an adjustable holdfast that came with a flanged mounting hole fixture. Apparently some had a backing plate as well, so you sandwich the bench between the cast iron flange and what looks like a sheet steel plate. Main problem is, you only get one mounting location for your holdfast unless you buy others (looks like Axminster may sell spares). I picked up a Woden one at the flea market a couple of years ago - the flanged casting is pretty solid. Google "Woden Holdfast" and you can see the sandwich arrangement- you should be able to make it from pipe fittings. Here is a Woden like the one I have, with the flanged fitting on the holdfast shaft: