Hi folks,
I've noticed that the little grub screws for adjusting SME arms can be easily graunched. The readily available 1.5mm hex keys are a loose fit in the screw socket, and if there is already some wear there could be a problem with a tight one. No adjustment!
I had a close call with my arm, and am now very careful not to overtighten.
Did SME provide a custom key for their arms? Can we get them?
Cheers, Nam
I've noticed that the little grub screws for adjusting SME arms can be easily graunched. The readily available 1.5mm hex keys are a loose fit in the screw socket, and if there is already some wear there could be a problem with a tight one. No adjustment!
I had a close call with my arm, and am now very careful not to overtighten.
Did SME provide a custom key for their arms? Can we get them?
Cheers, Nam
Hi,
Its because SME use AF sizes not metric.
Available from your local "everything a pound" shop.
🙂/sreten.
Its because SME use AF sizes not metric.
An externally hosted image should be here but it was not working when we last tested it.
Available from your local "everything a pound" shop.
🙂/sreten.
SME graunching update
Hi Sreten and folks,
I've tried the Blackspur keys.
Unfortunately this 'small' matter is a little more complicated than I thought. Under a glass with micrometer, the 1.5mm and 1/16" keys are identical, and both are too small in section for the SME grubscrews, the same goes for Proskit 1.5mm keys of course, which are a little sharper in section than the Blackspur but still too small.
There is a company, I don't know if I can mention them here, who supplies AF keys measured in mms across the flats. They have 1.5mm and 1.6mm AF and I am going to try these.
Given the value and collectability of some SME arms, and the problem of stuck grubscrews, I think it's worth getting just the right keys.
Lucky I caught mine in time, before it was too late!
Cheers, Nam
Hi Sreten and folks,
I've tried the Blackspur keys.
Unfortunately this 'small' matter is a little more complicated than I thought. Under a glass with micrometer, the 1.5mm and 1/16" keys are identical, and both are too small in section for the SME grubscrews, the same goes for Proskit 1.5mm keys of course, which are a little sharper in section than the Blackspur but still too small.
There is a company, I don't know if I can mention them here, who supplies AF keys measured in mms across the flats. They have 1.5mm and 1.6mm AF and I am going to try these.
Given the value and collectability of some SME arms, and the problem of stuck grubscrews, I think it's worth getting just the right keys.
Lucky I caught mine in time, before it was too late!
Cheers, Nam
can you get the grub screw out?
If so, get a small bolt that fits, grind the end to a point (i assume the origional grub screw has a point), cut it to length (cutting the bolt head off) and cut a slot in the end so you can use a small screw driver.
Just a thought, without owning this are, or seeing where the screw is, but ive replaced a few grub screws this was.
Small allen head bolts/grub screws are prone to rounding out.
If so, get a small bolt that fits, grind the end to a point (i assume the origional grub screw has a point), cut it to length (cutting the bolt head off) and cut a slot in the end so you can use a small screw driver.
Just a thought, without owning this are, or seeing where the screw is, but ive replaced a few grub screws this was.
Small allen head bolts/grub screws are prone to rounding out.
graeme uk said:
Only if you don't use the correct key! Try an engineering shop rather than a cheap and cheerful shop. They will have more choice and better quality. As far as I remember, the SME uses British Association grub screws (6BA).
Hi audio-kraut,
When you insert the key into the screw, try checking how much play there is. With mine, and the 1.5mm Proskit key or 1/16" equivalent, I can turn the key a quarter turn without resistance. This is very sloppy. On tightening, I found that the key slipped round under pressure, and I didn't try it again. Under a glass, there is only a little graunching so far.
I'm still waiting for some specialist keys to arrive in the mail.
Cheers, Nam
When you insert the key into the screw, try checking how much play there is. With mine, and the 1.5mm Proskit key or 1/16" equivalent, I can turn the key a quarter turn without resistance. This is very sloppy. On tightening, I found that the key slipped round under pressure, and I didn't try it again. Under a glass, there is only a little graunching so far.
I'm still waiting for some specialist keys to arrive in the mail.
Cheers, Nam
SME graunching - problem solved!
Hi folks,
I have obtained some keys from a model engineering company.
These are 1.6mm AF hexagon keys and are a snug fit with the SME. They would probably even work with worn grubs.
Looking at the standard 1.5mm or 1/16" keys there is a big difference even to the naked eye; these custom keys are much more substantial.
If anyone wants the link, just PM me. The keys were 50p each plus p&p.
Cheers, Nam 🙂
Hi folks,
I have obtained some keys from a model engineering company.
These are 1.6mm AF hexagon keys and are a snug fit with the SME. They would probably even work with worn grubs.
Looking at the standard 1.5mm or 1/16" keys there is a big difference even to the naked eye; these custom keys are much more substantial.
If anyone wants the link, just PM me. The keys were 50p each plus p&p.
Cheers, Nam 🙂
Hi,
Well the Blackspurs claimed to be A.F. sizes, obviously not. Seems
that you get what you pay for. An AF set should have these sizes :
1/16" 5/64" 3/32" 1/8" 5/32" 3/16" etc i.e. they are imperial.
🙂/sreten.
Well the Blackspurs claimed to be A.F. sizes, obviously not. Seems
that you get what you pay for. An AF set should have these sizes :
1/16" 5/64" 3/32" 1/8" 5/32" 3/16" etc i.e. they are imperial.
🙂/sreten.
Hi sreten,
No worries, and thanks again for your help and the useful photo. The Blackspurs will come in handy for my mountain bike, so I'm happy all round.
I know that this was a bit of an 'anorakish' thread, but I really didn't like it when that loose key slipped.
By the way, the magnifier with micrometer scale was readily available at Maplins and should come in handy for checking worn stylii, so that's another positive. Every home should have one. LOL
Cheers, Nam 😉
No worries, and thanks again for your help and the useful photo. The Blackspurs will come in handy for my mountain bike, so I'm happy all round.
I know that this was a bit of an 'anorakish' thread, but I really didn't like it when that loose key slipped.
By the way, the magnifier with micrometer scale was readily available at Maplins and should come in handy for checking worn stylii, so that's another positive. Every home should have one. LOL
Cheers, Nam 😉
sme graunching
Hi nam402, sreten
The founder of SME, Steyning UK (Mr Alastair Robertson-Aikman) was originally a modeler and the original business catered for guys playing with chookchooks. I am also one but don't play with trains or steam engines. All these guys originally used BA fasteners and the handtools for these.
bulgin
Hi nam402, sreten
The founder of SME, Steyning UK (Mr Alastair Robertson-Aikman) was originally a modeler and the original business catered for guys playing with chookchooks. I am also one but don't play with trains or steam engines. All these guys originally used BA fasteners and the handtools for these.
bulgin
Hi folks,
I just got an email back from SME and they say that they always recommend 1/16" keys. That's all. They suggest that my grubs are worn.
The plot thickens.
As I said before, 1.5mm and 1/16" keys are indistinguishable under the micrometer and both too small. My new 1.6mm AF keys are visibly larger and are a snug fit in the grub screw. They slide nicely to the bottom of the recess and there is very little play side to side.
I have tested the 1.6mm AF with both worn and new grubs and the fit is perfect.
How can you beat that? Proof of the pudding.
Cheers, Nam.
PS, Yep, I have built a few model aeroplanes myself, so I guess I am quite sensitive to small scales. It' s a small world!🙂
I just got an email back from SME and they say that they always recommend 1/16" keys. That's all. They suggest that my grubs are worn.
The plot thickens.
As I said before, 1.5mm and 1/16" keys are indistinguishable under the micrometer and both too small. My new 1.6mm AF keys are visibly larger and are a snug fit in the grub screw. They slide nicely to the bottom of the recess and there is very little play side to side.
I have tested the 1.6mm AF with both worn and new grubs and the fit is perfect.
How can you beat that? Proof of the pudding.
Cheers, Nam.
PS, Yep, I have built a few model aeroplanes myself, so I guess I am quite sensitive to small scales. It' s a small world!🙂
Hi,
I suspect the cheapo 1/16" AF is simply a stamped 1.5 mm.
How about the 1/8" cheapo AF, 3 mm or 3.2 mm ?
As you say a 1/16" AF = 1.6 mm.
🙂/sreten.
I suspect the cheapo 1/16" AF is simply a stamped 1.5 mm.
How about the 1/8" cheapo AF, 3 mm or 3.2 mm ?
As you say a 1/16" AF = 1.6 mm.
🙂/sreten.
Hi sreten,
At the risk of boring us all to death, this is still a little more complicated.
The cheap 1/16" key is only 1.5mm from corner to corner. Under the micrometer it is a fraction under 1.4mm measured across the flats.
This is the same with the Proskit and the Blackspur, although the Proskit is sharper at the corners, which helps. The Blackspur is both too small and quite undefined on the corners, which is not good in a tight grubscrew.
My specialist hex key is 1.6mm across the flats and 1.7mm from corner to corner. It is also sharply defined and well made. Hence the good fit.
Anyway, that's pretty much all I have to offer. I'm beginning to think I could submit an academic paper on this subject LOL
Cheers, Nam
Oh, and the 1/8" cheapo is 3mm AF
At the risk of boring us all to death, this is still a little more complicated.
The cheap 1/16" key is only 1.5mm from corner to corner. Under the micrometer it is a fraction under 1.4mm measured across the flats.
This is the same with the Proskit and the Blackspur, although the Proskit is sharper at the corners, which helps. The Blackspur is both too small and quite undefined on the corners, which is not good in a tight grubscrew.
My specialist hex key is 1.6mm across the flats and 1.7mm from corner to corner. It is also sharply defined and well made. Hence the good fit.
Anyway, that's pretty much all I have to offer. I'm beginning to think I could submit an academic paper on this subject LOL
Cheers, Nam
Oh, and the 1/8" cheapo is 3mm AF
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