Holdfast clearance?

[Dale Murray]

I am starting to ruminate on my bench design and would like to know the clearance under the bench required by a holdfast. I know this has a lot to do with how thick the material its holding. The reason this is a concern is I desire a shaker style bench but will need to allow clearance between the bottom of the top and the cabinet storage below.

My top, which I already have, is 2.25" thick maple. Maybe a holdfast will not even grip in a top that thick.

Thanks for the help.

[Jim Leslie]

Up until recently my benchtop was only 2" thick and my holdfasts held just fine. I have since doubled that to 4" and it is somewhat better. I suppose if you allow enough room under to accommodate the thinnest piece you plan to hold you should be ok. There were numerous times I had to clear out the various items underneath to use the holdfasts!

[Matthew N. Masail]

I'm doing the same thing right now. I'd just measure your holdfast projection under the table when it's not holding anything and add a little bit. I'm adding enough so I can also place my shooting boards on top of the storage cabinet and not worry. Keeping shooting boards there will also prevent me for using that shelf for junk

[Jim Koepke]

I'm doing the same thing right now. I'd just measure your holdfast projection under the table when it's not holding anything and add a little bit. I'm adding enough so I can also place my shooting boards on top of the storage cabinet and not worry.

Everyone does things differently for good reason. For me keeping tools in a cabinet under the bench doesn't work. That's one reason milage varies.


Keeping shooting boards there will also prevent me for using that shelf for junk

You must have stronger will power than me.

My hold fasts are stored on a shelf under the bench top, on top of all the junk.

jtk

[Chris Hachet]

I am using the Gramercy hold fasts, they work just fine in 1/ 1/2 inch thick SYP, as well as in maple and beech. I do not use a cabinet under my bench as I find holdfasts very helpful, and have several holes for them.

[Matthew N. Masail]

Everyone does things differently for good reason. For me keeping tools in a cabinet under the bench doesn't work. That's one reason milage varies.



You must have stronger will power than me.

My hold fasts are stored on a shelf under the bench top, on top of all the junk.

jtk
Jim I didn't mean that he SHOULD do what I'm doing, just sharing my take on it. My shop is tiny, so storage under the bench is a must. I won't store every minute tools there but the space will be welcome. As far as will power goes.... Well, It's taken 5 years in a small messy shop to force me to develop "order" habits.... And I use tricks to keep me in order like having a place for everything, a dedicated clutter area, and as an example the shooting board thing. I still need a comfortable way to put things back so most used tools go on a ply board on the wall behind the bench. Small dedicated drawers at standing height work nicely too. For me it's a need, I can't work in a mess, but YMMV!

[David Nelson1]

You could use a pieces of scrap to make the difference, which BTW you should be doing to avoid tooling marks.

[Jim Koepke]

Jim I didn't mean that he SHOULD do what I'm doing, just sharing my take on it. My shop is tiny, so storage under the bench is a must. I won't store every minute tools there but the space will be welcome. As far as will power goes.... Well, It's taken 5 years in a small messy shop to force me to develop "order" habits.... And I use tricks to keep me in order like having a place for everything, a dedicated clutter area, and as an example the shooting board thing. I still need a comfortable way to put things back so most used tools go on a ply board on the wall behind the bench. Small dedicated drawers at standing height work nicely too. For me it's a need, I can't work in a mess, but YMMV!

Matthew, Sorry if my reply gave you the wrong impression.

I also strive to keep my bench 'less cluttered.' Though it seems the clutter grows when I am not in the shop.

jtk

[ian maybury]

I guess the basic is that the straight shank of a holdfast in order to function needs to clear the bottom surface of the bench. Not necessarily by very much, but enough to ensure that any rounded off part at the end is safely clear of the dog hole. i.e. they grip as a result of the exposed end hooking under the bench top lower surface. This because its clearance in the dog hole and the tilting force generated by the clamping action allows it to tip a little sideways - while the force trying to dislodge it is almost vertically upwards. Tapping the holdfast sideways releases it because it stands the shank up close to vertical.

The space required underneath the top after that is going to be down to the length of the straight shank of the actual holdfasts you plan to use, the thickness of your thinnest work and the thickness of your bench top. i.e. it depends.

Dogs don't grip so well in very thick tops, probably because the tilt angle is typically much reduced and so 'hooking under' becomes more difficult/slipping upwards much easier.

That suggests that the thicker the bench top the larger the diameter of the dog hole needs to be for a given holdfast shank diameter to maintain the same tilt angle and so get a good grip - but definitely run some tests in scrap before committing anything. Dogs seem to work well in stock thinner say 2in thick bench tops using the clearance provided by a 3/4 in drill or router bit, so a thicker top probably suggests a requirement for a slightly larger drill or cutter to restore this tilt angle. The downside of this method is that it could cause problems using other dog hole mounted equipment like the Veritas bench dogs or stock 3/4 in round dogs which to grip rely on the hole size being correct for them.

One alternative to get around this is probably to counterbore the dog/holdfast holes from below so that the effective bench top thickness is reduced. (but again test before committing) This may have the effect too of permitting the use of a shorter shanked hold fast like the Grammercy - and of reducing the free space required under the top/above your storage....

[Jim Koepke]

The downside of this method is that it could cause problems using other dog hole mounted equipment like the Veritas bench dogs or stock 3/4 in round dogs which to grip rely on the hole size being correct for them.

My thought on this is to have a separate row of holes for dogs and holdfasts. Most of the time it seems my needs would be better served if the holdfasts were a little further in from the edge than where the dog holes are.

jtk

[Richard Line]

I went through this same consideration with my bench. I required drawers under my bench (very limited storage space in my 'shop') and I wanted to use the Gramercy holdfasts. I decided I would have to cut a bit off the holdfast's shanks (maybe an inch). That was easily done with a hack saw and some clean up. With my 2-3/8" thick top, that still allows me to clamp a 3-1/2" piece down.

For questions about using the Gramercy holdfasts on different thickness bench tops, check out their advice on their web site. It work good for me, even for use on a saw bench.

[ian maybury]

I'm just finalising my own (long running) bench layout Jim - so i don't have the user experience to have a view on the subtleties of bench layout...

[Dale Murray]

Thanks for all the good responses.

This will be my first, and hopefully last bench.

My intent is to have a series of dogs on the front and rear edge that will work with my chain vise.
As for the holdfasts I will drill holes in the top as needed, letting the need dictate the location. I may find I only need 2-3 locations. I read a story about somebody who put in a bunch of holes while building his bench and found he didn't like the location of any of them, thus had to drill more; I'll learn from his mistake.

[Jim Koepke]

As for the holdfasts I will drill holes in the top as needed, letting the need dictate the location. I may find I only need 2-3 locations. I read a story about somebody who put in a bunch of holes while building his bench and found he didn't like the location of any of them, thus had to drill more; I'll learn from his mistake.

Ouch! Those are the kind of lessons best learned from someone else.

There are only about 3 or 4 holes that are used for my holdfasts. So your plan sounds great. Besides, if another place is needed, drilling a hole is quick work.

jtk

[Richard Hutchings]

That's what I've done as well. Holes as needed that is.


Ouch! Those are the kind of lessons best learned from someone else.

There are only about 3 or 4 holes that are used for my holdfasts. So your plan sounds great. Besides, if another place is needed, drilling a hole is quick work.

jtk

[John Sanford]

With your planned holdfast in hand, using a piece of stock the thickness of your top (or using your top), drill a hole for the holdfast. Drop the hold fast through and seat in in the hole. Measure the amount of shaft projecting out the bottom of the hole. Add a 1/4" to 1/2" "just because." That's your clearance.

If you plan on keeping anything else on top of the cabinet unit, add the pertinent "heights" in as well.

The extra "just because" allows you to put thin things (pencils, rulers, etc) down there without worry. You want to measure against the actual workbench top simply because doing so allows you to casually drop the holdfast into a hole so it's "at ready." The other thing using the actual top rather than top + thinnest thing does is protect you from seating a holdfast on something that fails/breaks, resulting in the holdfast extending further below than planned.

[Reinis Kanders]

I have 3" thick top and 9" space for holdfasts under it. Those 9" work well because I can put most used planes on that shelf and never have any issues.
Also Veritas holdfasts come with optional shorter 5" leg.