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Metal bolts in timber threads.

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Blog entry by LittleBlackDuck posted 07-31-2017 01:41 PM 2009 reads 1 time favorited 22 comments Add to Favorites Watch

Boys and Girls, if you are only interested in bargain basement solutions, please jump in the lift and press “G” for “Going Down to the bargain basement”, exit the lift and go home without reading further.

I am here to readily assist you in parting with your hard earned shekels without remorse, and if you are interested in a better solution (at a cost), read on. No… I don’t have shares in the product and the retailer is not related to the ”waterfowl family Anatidae” (Ducks 2u).

In the past I have occasionally used metal bolts in timber by cutting the timber thread using an appropriate tap from a low end tap and die set.

I labelled the oft used taps so I didn’t have to think each time,

Then one day when I was trying to find that elusive imperial bit of hardware in our local dedicated fasteners retailer, I saw a set of taps and associated drill bits designed to handle our standard metric hardware and advertised as specifically suitable for woodworkers. Being a sceptic, I was mesmerised by the ad and even though I thoroughly quizzed the sales person, soon after I was heading back to my workshop to test my new thread making kit.

I used to use this as a demo of wooden threads to woodworking guests in my workshop,

I’m not going to say that after that I always used metal bolts in timber threads, but when I have used them, I was never disappointed. I am continually amazed at the amount of pressure that could be applied before the humble timber turned into fire wood.

Back in February 2017 I saw this video about timber threaders being designed by “The Wood Whisperer ” and an accomplice. Being a fan of timber threads I couldn’t resist the temptation to place an order.

Today, August 2017 (a mere 6 moths later), my set of imperial and metric taps arrived. I immediately made a bee line (ok, teleported down using the phone booth) to my workshop and decided to compare my “original dedicated” 10mm tap with the newly arrived Spagnoulo (TWW) offering.

As always, it wouldn’t be a Duck’s Tale if I didn’t digress. I was vaguely aware that my newly acquisitioned NOVA Drill Press had a tap feature and under duress, I quickly perused the instruction relating to that function.

After a few button presses, the drill was configured to do some tapping (if only it could do the same with beer).

While the speed is displayed as 900rpm, for tapping it was automatically reduced to 100rpm (what a bonus).

Now let’s digress from the digression and waddle back to the story. I loaded each of the two 10mm taps and drilled the recommended holes.

Scurrying for a couple of 10mm bolts I was fortunate to find some as I would have had to tackle a couple of 12mm bolts with my die (and I didn’t want to die today… never thought about tapping 12mm holes… DOH!).

After threading the two bolts, I tried the wobble test… I passed it with flying colours as I hadn’t had a drink all afternoon, however, the original tap exhibited a slight wobble while the new tap was virtually immovable. Now I will reflect that I have not had any issues with the old threads as once the bolt was cranked up, all play was taken out. The TWW taps were designed with greater tolerances and to give you an indication, the old tap’s specs recommended an 8.5mm hole while the new one’s was suggested at 7.5mm. Overall the TWW threads were much tighter providing a more secure fit. As screwing progressed (hmm.. do you screw a bolt as you don’t bolt a screw… preferably, unless your old… I digress if you hadn’t noticed), I had to resort to using a spanner much earlier than the “original” tap.

Now not everyone taken in by my silken salesmanship will purchase the taps and then go out and spend $2,400 on a tap assisting NOVA drill press. Well for all you skinflints the TWW taps are just as much at home with the use of a drill (cordless, or for you senior seniors, a corded one) though variable speed is recommended.

When using the hand held drill, the lead in may not be exactly 90° but as you progress even just slightly in, it aligns with the pre drilled hole and creates as tight a fit as with the NOVA. The taps can be used in a drill with either a variable or hex chuck.

The new set is now ready to be bolted to the wall,

You may all wonder what was that lonely first picture doing… Well he’s part of the following conspiracy in presenting my acid test to all you skeptics out there… you know who you are!

Drilled a hole in a piece of pine and tapped it with a 10mm bit,

Remember the first picture? OK, here it is again in case the grey matter is having a sabbatical,

Decided to attack it with an 8mm allen key from the safety of my mini vice,

After a significant amount of torque and fear of risking another hernia, I eased up on the bolt,

You may have noticed that the head “countersunk” a good 5mm+ into the pine without affecting the integrity of the thread.

You may say it’s only pine… “It’s only pine!” That is why I managed to countersink, hardwood would (pardon the stutter) provide greater grip and countersinking resistance.

What does all this mean? Anyone wants a set of metric taps with complimentary drill bits. I paid $90 for the set and am prepared to relinquish it to a friendly home for maybe a donation of a cask of vino (locally).

For all those not interested in this topic, please go back and re-read the 1st paragraph and don’t bother to read the rest.

PS. If you all stay good Boys and Girls and eat all your greens, I may post a review about wooden threads. Some may scream NO MORE and by pure mathematics, the remainder didn’t, but you’ll all have nightmares wondering if and when.

-- If your first cut is too short... Take the second cut from the longer end... LBD



22 comments so far

View GR8HUNTER's profile

GR8HUNTER

2619 posts in 465 days


#1 posted 07-31-2017 02:29 PM

LMAO :<))

-- Tony Reinholds,Pa. REMEMBER TO ALWAYS HAVE FUN

View Redoak49's profile

Redoak49

2709 posts in 1741 days


#2 posted 07-31-2017 03:04 PM

I am eating my greens and waiting for the review…..

View bruce317's profile

bruce317

392 posts in 576 days


#3 posted 07-31-2017 03:34 PM

I’ll go with the above two, plus nightmares.

-- Bruce - Indiana - Sawdust is just, MAN GLITTER!

View JohnMcClure's profile

JohnMcClure

87 posts in 393 days


#4 posted 07-31-2017 05:16 PM

I’m hoping you discuss threading wooden dowels. And something about foie gras…

View Mainiac Matt 's profile

Mainiac Matt

7207 posts in 2081 days


#5 posted 07-31-2017 06:36 PM

There’s actually quite a lot to the geometry of bolts and threaded holes (for an exhaustive treatment of the subject, I recommend the Machinist Handbook).

Two of the key parameters are the major and minor diameters. Major diameter is what you measure when you put the flat faces of a caliper on the outer points of a bolt thread, and minor diameter is what you measure when you put the knife edges of a caliper as deep into the threaded grooves as possible.

The size of the pilot hole for the tapped hole is always larger than the minor diameter and smaller than the major diameter, and it will determine the amount of thread engagement (usually either 50% or 75%) between the surfaces of the bolt threads and the surfaces of the threads in the tapped hole.

Turning threads in harder materials (i.e. carbon steel) is very hard on the tooling and can break the tap in the hole if too much force is applied too quickly, so a larger pilot hole and less thread engagement is necessary for successful tapping, and it is acceptable, as the metals are hard and rigid.

For softer metals like aluminum and brass, more thread engagement is desired, as the metals are soft and can peen over (stripping the threads), but fortunately, these metals also cut more easily, so you can use a smaller pilot hole.

There are a lot of different styles of taps for threading holes as well, but the two major categories are cutting and forming, with the former cutting out the metal and the later pressing the geometry into the metal (these are usually used on high volume production applications). Cutting taps (pretty much what all hobby peeps have experience with) vary in the number of cutting flutes (typically 2, 3 or 4), the material (carbide or tool steel), the coatings (none, cobalt or tin) and taper of the leading edge.

So for threaded holes in wood, you would ideally have a pilot hole that was just a shade over the minor diameter of the bolt and the tap would be a cutting tap with nice deep grooves in-between the cutting edges to remove the wood waste (probably 2 or 3 flute, with deep flutes) and likely don’t require as much of a taper to get the cut started.

Mark obviously did his homework and then either special ordered some odd ball taps of an existing design that were well suited for wood, or worked with somebody to come up with something new and had them manufactured to his specification.

-- Pine is fine, but Oak's no joke!

View tyvekboy's profile

tyvekboy

1663 posts in 2765 days


#6 posted 07-31-2017 08:52 PM

Another great post. Thanks for making me aware that such tools exist and where to find them.

-- Tyvekboy -- Marietta, GA ………….. one can never be too organized

View LittleBlackDuck's profile

LittleBlackDuck

1118 posts in 573 days


#7 posted 07-31-2017 09:01 PM


..... for an exhaustive treatment of the subject, I recommend the Machinist Handbook).....

- Mainiac Matt


Phew MM, that is one technical explanation. I was going to mention all that in this post but somehow it must have just accidentally slipped my mind or got lost amongst my scientific layman’s prattle.

You have found my Achilles heel. For someone that burdens others with long winded posts, I have this abhorrent trepidation of reading. For this transgression, I have been chastised countless times.

You are 100% correct in surmising Mark had external help, and they did have the taps made to their specifications, hence the 6 months wait. He and his co-designer have released some videos which I have alluded to as he explains the threader much better than I ever could.

The main intention of this post is to get the point across that metal bolts in a wooden thread seem to have a place in the workshop and if people are inclined to venture down that path, Mark’s little puppies (if one is prepared to pay that few extra shekels) do a better job than the taps most people would have access to through the normal home hardware type of tap and die sets.

I suppose having said all that, the jury may still be out on their endurance during seasonal wood movement, however, I believe that somewhere I read (correction saw in a video) that it didn’t seem an issue.

-- If your first cut is too short... Take the second cut from the longer end... LBD

View LittleBlackDuck's profile

LittleBlackDuck

1118 posts in 573 days


#8 posted 07-31-2017 09:03 PM



.... Thanks for making me aware that such tools exist and where to find them…..

- tyvekboy


No woories t’k’, that was my primary intention.

-- If your first cut is too short... Take the second cut from the longer end... LBD

View htl's profile

htl

2895 posts in 912 days


#9 posted 07-31-2017 10:22 PM

Very interesting, now will store this in the back of my memory and will have to ask for help to find it when I really need it, but the info is there so I know it can be done and looks to hold surprisingly well I must add.

-- There's a hundred ways to do anything, alot depends on the tools at hand.

View WoodPixel's profile

WoodPixel

9 posts in 1950 days


#10 posted 08-01-2017 08:36 AM

If you are still willing to relinquish those metric bits and drills, Id gladly take them off your hands :)

Ive even a project to use them on this week! Hows that!

-- Evan, Australia, woodPixel.com.au

View robscastle's profile

robscastle

4185 posts in 1957 days


#11 posted 08-01-2017 09:15 AM

Well I think I will make a bolt for the “workshop” and see how all this spirals out.

Stand by I may screw up!

Hey how does the Teleporter work? ...a blog would be good
BTW I think I may have dropped my wallet in your workshop some where its got a wad of cash in it!!

-- Regards Robert

View LittleBlackDuck's profile

LittleBlackDuck

1118 posts in 573 days


#12 posted 08-01-2017 10:05 AM


BTW I think I may have dropped my wallet in your workshop some where its got a wad of cash in it!!

- robscastle


Correction r’c’... HAD cash in it. Funny somehow the cash went missing and I also seem to have misplaced your wallet. I believe the salvos will send you a postage collect thank you note.

As for the Teleporter, it’s not a home made job but bought in anticipation of me having issues with my steps after my 120th. birthday. However, if you want s sneak view try this.

-- If your first cut is too short... Take the second cut from the longer end... LBD

View bj383ss's profile

bj383ss

187 posts in 2114 days


#13 posted 08-01-2017 10:41 AM

LBD I am not going to eat any greens but I am awaiting the next installment. Hopefully if I order some they won’t take 6 months to get to Texas.

Bret

-- https://www.flickr.com/photos/27291602@N03/

View Bluepine38's profile

Bluepine38

3370 posts in 2838 days


#14 posted 08-01-2017 04:41 PM

Good article, however, for us lazier people there is a threaded insert for wood that I have been using for a
long time. E-Z Lok is one of the manufacturers and they are available in most hardware stores and Home De
type stores. They offer a lag screw type thread on the outside and a bolt thread on the inside. With that said
there is something about cutting threads in wood that is more satisfying and challenging, both for the bolt
and the nut. I may not become proficient at it, but is fun playing in the shop and attempting it.

-- As ever, Gus-the 78 yr young apprentice carpenter

View andrewkleinWW's profile

andrewkleinWW

27 posts in 944 days


#15 posted 08-02-2017 12:22 AM

Thanks for this thoughtful and thorough (and funny) investigation of the taps.

- the accomplice

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