Bolt too tight - Cam belt idler bearing Ducati 900SS

[BillyJ]

I'm changing the cam belt roller bearings on my 900ss and one of them is held in with a bolt I can't undo.

The head has 2 parallel flat sides 10mm apart and then a radius on each side connecting them. Sorry no pic at the moment.

I've managed to deform the end of my 10mm spanner trying to undo it and don't know what the head type is called so I can get a socket for it.

Any advice?

I've used penetrating oil.

Edit: found this pic which shows what the socket would need to look like to fit over the bolt head
https://www.ecas2cvparts.co.uk/images/a1.2767.jpg


EDIT: Changed the title so anyone with this problem in the future can find it
____________________
Had: '06 CBR125R + '01 GSF600 + '07 SPRINT ST 1050 + '80 CB250 RSA + '93 Ducati 900SS
Have: '13 GSXR-1000 + '01 CB500S
"The aryan confuser"

[Nobby the Bastard]

[BillyJ]

[331X2]

You'd probably get a better pull off a good (Bahco or Irega, nothing else will do) adjustable spanner, a 12" one would be ideal.

[bugeye_bob]

it isnt a opposite thread is it ?

[BillyJ]

[Ed Case]

Is that an actual tensioner pulley (adjustable) or only a 'damper' roller ?. I f it is a damper unless the bearing inside it is knackered why do you want to remove anyway ?, is it necessary to remove it to swap the cam belt ?.

[BillyJ]

[sutty86]

Blow torch

[Ed Case]

[Rogerborg]

[BillyJ]

[bugeye_bob]

If you google this on the Ducati forums they suggest heat, it isnt a reverse thread so ignore my earlier question, but it was asked on the same forum,
failing the heat a big bar on ya spanner.
hth

https://www.ducati.ms/forums/57-supersport/125736-fixed-tensioner-assembly-belt-roller-bearing-2.html

[smegballs]

[Robby]

I've got some proper Irwin grips, and I'm free tomorrow.

[BillyJ]

I ordered the Irwin things but yes Rob come round whenever, see you then
____________________
Had: '06 CBR125R + '01 GSF600 + '07 SPRINT ST 1050 + '80 CB250 RSA + '93 Ducati 900SS
Have: '13 GSXR-1000 + '01 CB500S
"The aryan confuser"

[BillyJ]

Rob came (all over my face), and we (he) got one of them out with a big lever and some grips.

Other one is being too stubborn so may use heat at some point.

Is there a technique to heating bolts for removal?
____________________
Had: '06 CBR125R + '01 GSF600 + '07 SPRINT ST 1050 + '80 CB250 RSA + '93 Ducati 900SS
Have: '13 GSXR-1000 + '01 CB500S
"The aryan confuser"

[.....]

[bugeye_bob]

I have a small gas powered soldering iron that also works as a small blow lamp, ideal for heating just a small area like this.

This type of thing

https://www.raygrahams.com/products/130269-butane-pencil-torch.aspx?pv=50207&gclid=coyh2cs6ktecfuo6gwodv_8cxa

[BillyJ]

Irwin unfuckers didn't work, the bearing is in between sizes so the 10mm one is too small and 13mm one slips

Got a mapp torch onto it and it didn't help but I will try a few more times with the torch.

Current plan is to either drill it out or make a tool to undo it.
Have currently drilled out the center to 5mm but my drill bits aren't sharp enough anymore to keep going, I've got the hole as deep as where the thread starts.

Here is the bearing that Robby got out just for reference:
https://s29.postimg.org/ogl8htvir/IMG_20161226_162447.jpg

https://s29.postimg.org/fmuc0q8k3/IMG_20161226_162506.jpg

And here is the tool I've designed which I might try to get made somewhere, got a 3d printed prototype which fits fine so might be calling up metal fabricators in the new year if I still can't get it out

https://s28.postimg.org/4040q7iwp/bearingtool1.png

https://s28.postimg.org/s54q7x37d/bearingtool2.png
____________________
Had: '06 CBR125R + '01 GSF600 + '07 SPRINT ST 1050 + '80 CB250 RSA + '93 Ducati 900SS
Have: '13 GSXR-1000 + '01 CB500S
"The aryan confuser"

[Pete.]

Give me the across-flats size and the diameter across the round ends and I'll make you one no bother.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[Ed Case]

Strikes me as a lot of aggravation to do what ?, replace an item that's working OK and replace it with another and knowing Ducati it won't be cheap especially if it brings the thread out of the motor with it when you succeed.

[BillyJ]

[Pete.]

Despite being a simple-looking item this isn't a trivial part to make. The reason is the slot is 10mm wide but the radius is 6.2mm, which requires a 12.4mm cutter to achieve. Clearly you can't fit a 12.4mm cutter into a 10mm slot without making the slot also12.4mm.

One way you could make it is to over-run the 10mm cutter past the radius ends until it's cut the appropriate length flats and I could do this (and in fact would, if I had the job in my workshop so I could try something else if it didn't work), but with such short flats you really need the end-support of the slot to give the tool maximum chance of working without deforming the bolt or the tool.

So this is what I'm going to do - cut the slot 10mm wide up to the 12.4 length (blue circles in in the drawing below), then run a 6mm end mill (red circle) around to remove some of the material in the corners, then finish up the tiny left-behind bits with a broach cutter I have already made which is the exact shape of the bolt head.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[Pete.]

Tool is done.

I made broach cutter from EN8 steel, which is hardenable somewhat by turning the OD to 12.4 and milling flats to make it 10mm wide. This mimics the shape of the bolt head.

Next I took some more EN8 steel and milled the slot in it then cut the corners with a 5mm cutter as per the drawing above.

Hardening the broach cutter is a simple matter of heating it with a gas torch then quickly swirling it around in a bucket of cold water. after that I cleaned up the cutting face on my grinder and ground some relief in the sides to stop it jamming in the hole.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good