Which is at fault

[marcros]

I bought from Rutlands a 3/4" wood threading kit. The hole for the plain dowel to enter is 19.05mm. I also have some store bought 3/4" dowel which I thought would save some time and effort to make some wooden screw clamps. This evening, the store bought dowel will not fit into the hole of the threaded. The dowel measures, as best as I can measure it 19.25-19.5mm.

Now I know that technically the threaded is spot on, but my feeling is that it is pretty poor that it cannot accommodate a typical store bought dowel. The dowel itself was a pound a foot so I don't think that the tolerance was unreasonable and have no reason to believe that it was any better or worse than any other. Even if it was bang on 19mm, it would have struggled to fit.

Am I being unreasonable? I don't know whether to brave Rutlands customer services department, whether to try and open the hole a little (sandpaper?) or just pop each dowel on the lathe and sand off a tiny little bit whenever I need to use it. If they replace it, then the replacement will be the same.

Are the breaded ones any better? Are the I branded ones from elsewhere any better?

 

[PAC1]

Have you tried chamfering the dowel to get it started and then see if it will work?

 

[marcros]

I knocked the edge off with a bit of sandpaper and managed to get the dowel in an inch or so but it was siezed solid and had not hit the cutter. I will try chamfering it tomorrow and seeing whether that works but it seems to be the shaft that is the issue, not starting it as such.

 

[bugbear]

IIRC, threading blanks need very close tolerance, so most people (again IIRC)
turn their own.

BugBear

 

[marcros]

Perhaps I am wrong to criticise it them. My turning isn't up to that standard yet, but my sanding on the lathe may well be.

 

[swb58]

If you are going to put the dowel on the lathe have you got a 19mm open ender to slip on it to check the diameter. That will take out any guess work.

 

[AndyT]

There does seem to be only one (Chinese? ) source of new made threading tools regardless of where you shop, unless you pay two or three times as much for a vintage one so I don't think there is anything Rutlands can do except give your money back and leave you without a tool.

The size does need to be accurate and on the set that I have the male and female threads do match, so your best bet is to adjust the dowel. At least it's not too thin.

You may be better off making your own, as some woods are much better than others.

I was lucky enough to find an adjustable rounding plane which helps but they are rare.
I suggest you make a suitable gauge and get back to the lathe - an adjustable spanner might work well as an accurate gauge.

 

[marcros]

I will develop my turning skills. At least I can make the handle and thread a single piece that way.

 

[Carl P]

In my (limited) experience a bit on the thin side, no problem, a bit thick and it makes it much harder/impossible to get it in (as I believe a certain actress etc)

Cheerio,

Carl

 

[Walney Col]

Rutlands have no choice in what size to make a 3/4" threading tool - the standard was set at least a hundred years before we went metric and it will still be the same specification in another 100 years.

And of course by the same token 19mm will always be 19mm which will never ever be the root diameter of a 3/4" thread.

 

[monkeybiter]

And of course by the same token 19mm will always be 19mm which will never ever be the root diameter of a 3/4" thread.

not really the issue:- http://www.dictionaryofconstruction.com/definition/root-diameter.html

 

[deserter]

I too have always aimed to be 0.5mm under sized, another thought is have you soaked the timber in oil of any sort? I use linseed and soak for differing lengths of time for different timbers. On beech for example I apply a very heavy coat, leave it 15 mins, wipe off the excess and start threading. Walnut I leave 30 - 40mins and oak several hours.

 

[marcros]

I dipped it in oil but didn't soak it. I had expected it to be half a mm oversized so that it would take bought dowel straight off but I suppose that would make the tool out of spec.

Anyway, I will keep trying and see what works.

 

[marcros]

Rutlands have no choice in what size to make a 3/4" threading tool - the standard was set at least a hundred years before we went metric and it will still be the same specification in another 100 years.

And of course by the same token 19mm will always be 19mm which will never ever be the root diameter of a 3/4" thread.

It was a 3/4 tool and 3/4" dowel. I measured in it metric to avoid having decimal inches which don't mean a great deal to me.

 

[Sheffield Tony]

I would have thought that the difference between a bone dry 3/4" dowel and a slightly damp one might be enough to make life difficult too ?

 

[Andy Kev.]

I encountered the same thing when I recently bought a threading kit of a different (and much more expensive) design:
http://www.fine-tools.com/gewind.htm

The 1 inch kit is billed as 25 mm i.e. 04. mm less than 1 Inch. So I thought that 25 mm beech dowel from the local DIY store would work quite easily but I had to trim it down. This was easily enough done by taking off very thin shavings from all around the circumference with a block plane (took less than 2 mins). I assumed - perhaps mistakenly - that the manufacturer made the thing a bit on the tight side because while you can live with "a bit snug", a case of "a bit slack" could lead to worse than useless results because the threading presumably needs to cut through as much wood as possible in order to produce maximum efficiency in the screw.

Having seen this thread I'm not not sure if the makers are erring on the safe side or if they have just got their tolerances wrong. For what it's worth I'm quite happy to know that I have to trim the wood as it means that I have to get the size just right for the threader, which must mean getting optimal results.

 

[dickm]

Just wonder if the OP is riding for a fall anyway using shop bought dowel for this application anyway. IMHO, not many woods take a good thread; box, fruitwoods and one or two others are best and the sort of dowel that's generally stocked is far from ideal. Might be better to do a bit more practice on the lathe and produce blanks in a close-grained hardwood.

 

[xy mosian]

I was lucky enough to find an adjustable rounding plane which helps but they are rare.

I wonder if one of these, perhaps with a modification here and there, might work.
http://www.ashemcrafts.com/products_stail_engine.aspx

xy

 

[marcros]

Just wonder if the OP is riding for a fall anyway using shop bought dowel for this application anyway. IMHO, not many woods take a good thread; box, fruitwoods and one or two others are best and the sort of dowel that's generally stocked is far from ideal. Might be better to do a bit more practice on the lathe and produce blanks in a close-grained hardwood.

quite probably. good practice all the same, if I cant turn a dowel, there probably isnt much hope for more complex turning, or the chess set that is at the back of my mind for time to come!

 

[marcros]

I was lucky enough to find an adjustable rounding plane which helps but they are rare.

I wonder if one of these, perhaps with a modification here and there, might work.
http://www.ashemcrafts.com/products_stail_engine.aspx

xy

interesting tool. thanks for posting that, I havent seen anything similar before.