Holdfasts

[bugbear]

Can you measure the marked distance ?

I suspect it's 4", but 5" and 6" are also candidates.

In a brace this distance is called the "swing", and is the radius
of the circle the handle makes in use. The diameter of this circle
is called the "sweep" of the brace, and is the number
normally quoted. Thus, a "10 inch brace" would more properly
be a "10 inch sweep brace", with a swing of 5 inches. I've asked
you to measure the swing of your brace.

BugBear

 

[DigitalM]

BTW given it's oak you were drilling through you might want to give the bit a tickle with a needle file to touch it up. Little and often in the key with augers to help maintain their geometry.

After recent discussion, where the balance seemed to be that the specific auger bit files were handy, worked, and above all safer in the hands of an idiot noob (cough), I invested in one, watched a dozen YouToob videos and fettled me bits (!!). They're nice and sharp. The problem I had was the oak getting fouled in the snail threads, which would then stop it being pulled into fresh wood. For every hole I had to back out a couple of times and clear it off. I tried waxing it (the snail that is!!) but that didn't really help much. I believe there are fine and course threads, fine for hardwood - maybe mine are course and that's the issue? It was like 4am when I was doing this so I just pushed on, but it would be good to know if there are ways to minimise this.

Serious point though, I wouldn't want to do this with less than a 10" sweep given the choice.

Oh dear God, OK, will add that to the car boot snoofling lookout/wish list. But yeah, I'm no "97lb weakling", but it got my biceps pumping!

 

[Phil Pascoe]

I gave one away not long ago .............. :lol:

 

[DigitalM]

Can you measure the marked distance ?


I suspect it's 4", but 5" and 6" are also candidates.

In a brace this distance is called the "swing", and is the radius
of the circle the handle makes in use. The diameter of this circle
is called the "sweep" of the brace, and is the number
normally quoted. Thus, a "10 inch brace" would more properly
be a "10 inch sweep brace", with a swing of 5 inches. I've asked
you to measure the swing of your brace.

BugBear

OK, it turns out that:

• You're all correct
• I have a titchy brace
• It was so late I was hallucinating
• I've only got myself to blame for how my arm feels this morning!

Yes, it's a 4" swing [cough].

Well, on the plus side, I can buy something and make auger bit work less "bracing".

Thanks for all the tips everyone, chatting away on UKW produces so much more interesting and useful information quicker and more to the point than 10x as much googling (which I also do, and youtubing, and reading old books, and magazine, and blogs...)

 

[DigitalM]

I gave one away not long ago .............. :lol:

Have you got any tools left Phil!

 

[Phil Pascoe]

About three times as many as I'll ever need - about 10 times in the case of chisels, although I did get rid of about 150.

 

[DigitalM]

About three times as many as I'll ever need - about 10 times in the case of chisels, although I did get rid of about 150.

PM me if you have any skews or dovetailing specific extras to sell. That's going to be my focus for a while early next year. I've pretty much got my basic marples set together now.

 

[MusicMan]

I agree about the size of the brace - yours is perhaps 8" swing?

From experience, the small increase in size by going up one step makes a big difference.

I'm trying to quantify the effect of swapping sizes. I can visualise the brace as a lever, pivoting about the centre of the bit. So going from 8" to 10" would only add 25% of [something] though going from 8 to 16 would add 100%, ie double it. Is that mathematically right? Is there a term for that number - advantage? I realise one cutting edge is behind the fulcrum and one beyond it, so assume they cancel each other out and that complication can be ignored.

Your'e right, Andy. It's called mechanical advantage (the advantage over holding the drill bit itself!). A clear way of thinking about it is that the torque=force times distance from the fulcrum, so indeed you get 25% more torque going from 4" to 5" radius.

The cutting edges don't affect the torque itself. The force on the cutting edges = torque divided by distance of cutting edge from the fulcrum. So the forces don't cancel out, rather they increase as the size of the bit increases, and they are the same on both edges.

Keith

 

[ED65]

The problem I had was the oak getting fouled in the snail threads, which would then stop it being pulled into fresh wood.

Ah yes, this is the commonest cause of augers stopping drilling well (or at all) according to something I was reading literally only yesterday!

I believe there are fine and course threads, fine for hardwood - maybe mine are course and that's the issue?

Yes, and possibly yes. TBH this may be par for the course though. Imagine if you were using a finer-threaded lead screw and it was clogging more :shock:

I know you fettled the auger, but I presumed that was confined to the four cutting edges. What's the condition of the lead screw's thread like? If it/they aren't 100% it can directly lead to problems because there isn't an uninterrupted channel for the dust/swarf to travel along.

 

[DigitalM]

I know you fettled the auger, but I presumed that was confined to the four cutting edges. What's the condition of the lead screw's thread like? If it/they aren't 100% it can directly lead to problems because there isn't an uninterrupted channel for the dust/swarf to travel along.

I didn't do the trick that I've seen of driving the screw into some wood with some cutting compound. I could try that. The screw is uninterrupted and deep - visually I think it's fine. I bought three at once, all Ridgway 240 series. 1/4, 1/2 and 3/4. The 1/2 has an obvious problem where a former owner filed into the screw breaking the channel significantly, which is largely why I decided to invest in the dedicated file for this purpose. I'm not bothered though as the total for the three was around £7 and I know now exactly what to look for having looked into these a bit more.

Maybe it's the block nature of the wood I'm drilling into. It may have been glued under pressure to form a tight block or something, and be full of glue.

 

[bugbear]

The Good News is that 8" is my favourite brace size for driving/extracting screws.

BugBear

 

[DigitalM]

Hahahaha, no need to take a hacksaw to the holdfasts, look upon my ingenuity and weep, mere mortals!

Scorched the holes a bit, but you know, it's not supposed to be fine furniture. Still, it's all practice. I guess it's just heat built up in the bit. My Elu only does 1/2 and 3/8, maybe a 1/2" cutter would have acted more like a heat sink, or I should have just taken more time and progressive cuts.

 

[MusicMan]

Hahahaha, no need to take a hacksaw to the holdfasts, look upon my ingenuity and weep, mere mortals!

View attachment 27137171829

Yes I do that too, as I have drawers under the worktop ending about 150 mm below the bottom. I've done this for a couple of years now and it has never been inconvenient. It is also good practice, in that it obliges me to put some scrap between the worktop and the work!