anvil hold fast issue

[will52100]

Tried making another hold fast today, and like the first one I did I can't get it to hold for anything.  Basic design made to knock and lock in the pritchel hole.  It's a Refflingfhaus anvil, so it's pretty thick under the hole.  Used cold rolled that would fit with very little wiggle.  So what's going on here?  I don't use one much, as yet, but was working on a set of hawks and it would have been nice not to have to chase the flat bar around while fullering the ends.

[JHCC]

You probably need more wiggle room.  A holdfast jams against one side of the top of the pritchel and the opposite side of the bottom.  Also, make sure that the top piece has enough flex to create the spring pressure that holds everything together.

[will52100]

Thanks, I was thinking maybe it needed to be tighter, I'll try making it a bit smaller and see.  All the ones I've seen or used were on London pattern anvils with a fairly thin heel at the pritchel hole, the Refflinghaus is thick there and it's a drilled hole, so not a lot of offset available to lock.

[John McPherson]

For this application, gracile is more forgiving than robustus. You don't want the stem of they holdfast to drop straight down in use, you want it to bind at the top rear and bottom front. You also want a lot of spring in the arm down to the pressure foot. While the whole thing can be made from round or square stock, if made from heavy square to fit the hardy, the arm needs to be a rectangle, twice as wide as it is thick.

[will52100]

I thinned it down some and still no joy.  Maybe I need to go thinner?  The pritchel is 5" thick on that part of the anvil.  Also, the pritchel hole is chamfered at the anvil face, no sharp corner to dig in.  I played with it some then got feed up and continued other projects chasing the bar across the anvil face.

[JHCC]

Here's a side view of my holdfast. Note the angle of the shaft as it passes through the (vertical) pritchel hole. 

(I hope you all appreciate my impromptu pizza-box backdrop.  This is the kind of photo where you do NOT want a busy background.)

This shows the shaft of the holdfast laid across the pritchel to show their relative sizes:

[will52100]

Ahh, thanks, I got it and will make another out of substantially smaller stock.

 

Thanks

[Mark Ling]

what's your pritchel hole size? maybe we can than suggest a steel size.

                                                                                                       Littleblacksmith

[JHCC]

 By the way, the threads that are visible at the bottom of the shaft are not functional, but a relic of the material I used. This is made from one of a number of  square U-bolts my mechanic gave me; I think they were originally used to hold leaf spring packages onto a truck axle.

[JHCC]

Worth noting that the holding force of these beasties can be really strong. When mine is hammered all the way in, I can grab it and lift my 148 lb anvil off its stand.

[Frosty]

Hold fasts is a good place to use coil spring though mild works fine. A sharp edge isn't what grabs the shaft, it's friction generated by huge pressure when the steel is bent.

Below is a hold fast I made for holding RR spikes so the heads won't interfere. The large foot doesn't mar hot steel when tightened though I should've curved it up, as the inside edge bites thicker work. It's 1/2"  hot rolled rd.

Frosty The Lucky.

[will52100]

It's a 7/8" hole, 5" deep.  The hold fast I made was from 3/4" cold rolled, thinned out and curled on the holding end.  The second one I did was a bit cleaner but held no better, I then took it down in size, nearly to 5/8", still not holding.  Do I need to take it down to 1/2" or less?  I've got some 3/8" coil spring I haven't figured a use for yet that I've straightened out.  I'm thinking I may try it next, the 5" deep hole makes for less of an angle than a thinner heel, so if I'm not overthinking it too much I'll need to go a bit thinner than an anvil with a thinner heel section.

[John B]

57 minutes ago, Frosty said:

Hold fasts is a good place to use coil spring though mild works fine. A sharp edge isn't what grabs the shaft, it's friction generated by huge pressure when the steel is bent.

Below is a hold fast I made for holding RR spikes so the heads won't interfere. The large foot doesn't mar hot steel when tightened though I should've curved it up, as the inside edge bites thicker work. It's 1/2"  hot rolled rd.

Frosty The Lucky.

 

Hi Frosty,

To get some idea for others to work with re clearance/working angle needed, what diameter is your pritchel hole, and how thick is the anvil's heel

[JHCC]

19 minutes ago, John B said:

Hi Frosty,

To get some idea for others to work with re clearance/working angle needed, what diameter is your pritchel hole, and how thick is the anvil's heel

The dimensions of mine are:

Pritchel diameter: 9/16"
Pritchel height: 2" (anvil face to underside of heel on inner side of hole)
Holdfast shank diameter: 1/2"

[will52100]

So you've only got about 1/16" clearance, but with a 2" heel it lets you get more of an angle.  I'll try the 1/2" out and see how that goes, if not I'm afraid with the 5" heel I've got I'm going to probably have to go to the 3/8" spring stock.  Well, I wasn't using it for anything else, maybe it'll work for this.

Thanks

[rockstar.esq]

Will52100  I've seen people using hold fasts sized to work in the hardy hole as well.  The larger opening might give you more room for smaller stock to angle.

[Stash]

I've successfully made a few styles of pritchel hole holdfasts, but my current go- to is a chunk of salvaged 1 1/4" round with a 90 bend in it. Top leg is ~4", the other leg is~8". I drop the long leg in the hardie hole and put my work under the short leg. There's enough weight to hold things down. Gravity vs friction.

Steve

[JHCC]

1 hour ago, rockstar.esq said:

Will52100  I've seen people using hold fasts sized to work in the hardy hole as well.  The larger opening might give you more room for smaller stock to angle.

For example: this.

[SLAG]

There is a beginners exercise that teaches making a hardy hole holdfast in Lorelei Sim's book The Backyard Blacksmith pages 108-109. It features pictures and an understandable narrative for that project. The book is currently being sold at a remaindered price on a number of websites anywhere from approximately $8.50 t0 $12.00. (e.g. Half Price Books, or Amazon) & others.

Of course several of the blacksmith supply companies will sell it for the full retail price. (yeah the same gang that offer coal or coke for one dollar a pound. (shipping included.))

Gotta love a duck.

Regards to all.

SLAG.

[stockmaker]

Let me add some fat to this fire.  First of all, Hello Everyone, this is my first post.  I am a novice blacksmith, but a long time woodworker.  I have made and studies woodworking benches.  As you know woodworking benches use hold fast's to hold stock.  The hold fast's are the same as those used on an anvil, mine are all 3/4" round stock.  There is a rule for using hold fasts in bench tops, that being the top can not be thicker than 4" for the hold fast to work reliably.  If it is you have to back bore the hole from the underside of the bench top.  I keep mine at 3.5" which allows them to work fine.  Will52100, you might want to set up a test jig out of wood using your new hold fast, the 5" thickness of your pritchel hole may be the problem. 

[JHCC]

First of all, Stockmaker, Welcome!! There are a number of other woodworkers here, so you'll fit right in!

question: you're using 3/4" stock, but what is the diameter of your hole?

[stockmaker]

I put a micrometer on the one pictured, it is 1/32" under 3/4", the bench holes are 3/4". 

[Frosty]

The Pritchel hole on the 125lb. Soderfors is  5/8" dia. x 1 3/8" - 1 1/2" thick. The hold fasts that work best in the Soderfors are from 1/2" dia. hot rolled or coil spring.

The Pritchel on the 206lb. Trenton is 3/4" dia. x 1 1/2" - 1 3/4" and a bit. The hold fasts I use in the Trenton are from 5/8" hot rolled or coil spring.

The diameters for the Trenton vary as I find myself drawing stock down to fit and I have 1/2" all the time for the Soderfors.

Frosty The Lucky.

[will52100]

I hit reply, but don't know what happened to my post.  Anyway, thanks for the help, it's appreciated. 

A buddy of mine has basically the same anvil as me and he made a holdfast that works well, I'll head over in a couple days and see what the difference is and measure it.

I've got the Backyard Blacksmith book and had forgotten a hold fast was in it.  I don't see anything in the book that I'm doing differently.  I did read in another book that a square shank works better in a round hole, might have to go that rout.

Or maybe go the gravity or drill press vise grip method, we'll see.

I didn't have time to mess with it today, but did clean the grease out of the hole thinking it was maybe lubing the shank up and preventing it from locking.  Long story short, I was woking overseas a month on and month off and my smithy is under an open air drop shed and condensation was rusting the face so I greased it up before leaving.  When I get back I'd wipe it off with a  diesel soaked rag.  Cleaned it out with diesel, then acetone, still not locking.

[SLAG]

Another suggestion. Check out this video http://www.thirteen.org/programs/the-woodwrights-shop/forging-the-hold-fast/

It shows how to make two different hold downs, and a bench dog step by step.

Good luck,

SLAG.