myford super 7 tufnol gears

[DanielW]

I've got an headache,good luck in sorting it.

 

[Tinbasherdan]

The point is that when fitted onto the tumbler lever, the tumblers should spin freely by hand, now due to being oversized,wrongly profiled or whatever, the New ones will not turn freely at all, to the point where the 28t is pulling teeth from the 30t, WITHOUT bei g fitted to the machine in any way shape or form. So I understand where you are coming from danielw, but the spindle gear has absolutely zero to do with it , not being anywhere near at the time the gears are stripping

 

[mr_splatter]

Just went to look at the gears on my S7 and they are a rattly fit on the tumbler. Yours are definitely far too tight. The picture below shows my Mark 1 for reference.

 

[mr migwire]

i would be tempted to set about the wheels you have with a file, just to dress out a bit of material from the throats of the gears and then take a thou or two off of the nose of each gear, you have nowt to loose....... just a thought

 

[DanielW]

The point is that when fitted onto the tumbler lever, the tumblers should spin freely by hand, now due to being oversized,wrongly profiled or whatever, the New ones will not turn freely at all, to the point where the 28t is pulling teeth from the 30t, WITHOUT bei g fitted to the machine in any way shape or form. So I understand where you are coming from danielw, but the spindle gear has absolutely zero to do with it , not being anywhere near at the time the gears are stripping

Well without traipsing through the thread,I don't think you mentioned? the teeth are being stripped with the tumbler gears off the lathe,if thats the case they must be made of cheese.

 

[Tinbasherdan]

Gonna give myford a bell tomoro and see what sense I can get from them , I highly doubt I'll get anywhere, and then plan b Is Mr file

 

[brightspark]

make a gauge up from the cast gears with some thin plate and check against the tuffnol gears for comparison see where u need to remove material in stead of just guessing

 

[Wendelspanswick]

You could mould some Polymorph against the good gears as a guage!
http://www.maplin.co.uk/p/150g-polymorph-n58ch

 

[CRB]

You could mould some Polymorph against the good gears as a guage!
http://www.maplin.co.uk/p/150g-polymorph-n58ch

Or Plasticene

 

[ukracer]

Ask DoubleBoost for video lessons

Definitely not the same tooth shape, on your 'new ones'

And thereby lies the problem IMHO. The issue here is no one knows how the old gears got broken. Most likely a crash and rapid stop I would think. The new ones are breaking from the information I can see when they rotate even if OFF the lathe.

imagine a tooth form of V and then a slightly angled tooth with a point at the tip. That will work like a wedge. Tufnol is ok in compression (it also matters if its been made from rod or sheet) but has a lot less strength in tensile. So the act of rotating the thicker teeth when the form should be different could easily snap the tufnol teeth.

I cant think they have used rod instead of sheet as it would have shown up a long time ago for others....although its easier an cheaper so who knows.....

 

[ukracer]

Some night time reading.. http://bbs.homeshopmachinist.net/threads/33429-Phenol-Tufnol-gear-blanks It wont help much but its a good read,.

 

[ukracer]

I think I have found out how to show what I am trying to describe.

If you tried to mesh these two gears together you can imagine what would happen. Ignoring the fact one is a composite material. I am pointing out the form of the Ali one would press into the composite form an cause the teeth to snap.

 

[MattF]

I don't know but I would have thought the meshing would have been done via the adjustment knob on the tumbler lever when it engages into the slot ie it adjust to put less pressure on the tumbler gears?

There is no adjustment on a tumbler assembly. They have a grand total of three positions, (forward, disconnected, reverse), and neither the positions nor the gears are variable.

 

[MattF]

i would be tempted to set about the wheels you have with a file

There's little left of the gears he has, bar the odd few teeth.

 

[Pete.]

Some night time reading.. http://bbs.homeshopmachinist.net/threads/33429-Phenol-Tufnol-gear-blanks It wont help much but its a good read,.

Ironically, it would be a fair bet that the sheet of gear blanks in those pics were myford tumbler gears. I'd also be willing to bet that they never had many returns if any at all when he used to make them, and that now they have them outsourced.

 

[Tinbasherdan]

Spoke to myford, they are sending a pair out again and have asked me to return the others for testing

 

[brightspark]

Spoke to myford, they are sending a pair out again and have asked me to return the others for testing

id do some serious measuring with the new ones when u get them before use

 

[CRB]

I suppose they are 20DP like the rest. Set them up on the banjo until you get them running nicely, then measure the centres of the studs. Compare that to the tumbler mechanism.

It will also show you if they are concentric to the bore.

 

[jordan1]

I bagged my self a super 7 the other week, the only issue with it being the tufnol 30t gear had stripped on the lead screw tumbler , I rreplacedthem both with a pair from myford, pressed the studs in with about 1/1.5 mm free play as not to nip them, however I span the lead screw on the hand wheel and its stripped the 30t again. It did seem particularily tight too, with a fair bit of gear chatter. Any ideas?

These any good:- http://www.ebay.co.uk/itm/GENUINE-M...Garden_PowerTools_SM&var=&hash=item4d18669c9a

 

[CRB]

These any good:- http://www.ebay.co.uk/itm/GENUINE-M...Garden_PowerTools_SM&var=&hash=item4d18669c9a

I saw that last night or Sunday, but the dropdown menu shows a twin 30t in steel and not Tufnol.