Engineer advice please

Sean d

Sean d

Zorg Expert (I)
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British Zeds
Joined
Sep 29, 2015
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Location
Lincolnshire
Model of Z
Z3 2.8
I have 2 rear style 42 split rims at an engineering company as I snapped some of the bolts and ended up with 5 that I could not remove so took them to the engineering company 7 weeks ago, I rang them on Wednesday and applied a little pressure telling them That I am coming to the end of the build and needed the wheels. On Thursday I got a call saying that they couldn't be done as the drill bit kept slipping off the stud as it was rock hard, I informed that the studs are titanium, now I thought any engineering company worth their salt would find it very easy to drill and tap 6mm studs, is this the case, it would be a shame to write the wheels off
 
Probably time to take them elsewhere. If they are really that tough I would think that they could be spark-eroded but I have no idea whether this would be cost effective.
 
We did mine easily using Cobalt drill bits Sean. But I would expect an engineering company to have tried them?
Are there two broken ones next to each other in any of the wheels?

Tony.
 
t-tony said:
We did mine easily using Cobalt drill bits Sean. But I would expect an engineering company to have tried them?
Are there two broken ones next to each other in any of the wheels?

Tony.
Click to expand...
Unfortunately one wheel does have 2 next to each other pal
 
I think it is time to take them elsewhere, any good engineering company should be able to engineer a solution and if they have had them this long and not told you there was a problem that is not satisfactory.
 
Very sharp HSS or Cobalt drill bit (you can sharpen HSS, cobalt bits are usually coated and can't be sharpened without damaging the coating)
Shortest possible drill bit length
Centre punch workpiece
Very slow drill speed (10s of rpm, rather than 100s) e.g. 4mm drill bit - use 70rpm
Lots of coolant (do not allow workpiece to show any signs of heat - if it does, you may need specialist tooling [spark erosion])
Push hard on drill bit for very short time on each "pass"
Do not allow drill bit to dull, keep drill bit very sharp (either by changing the bit or sharpening it)
Drill about 1-2mm on each "pass" and remove bit to remove swarf and allow workpiece to cool

Remove bolt threads from female thread with a pick
You won't be able to remove them with a tap without causing damage
When all traces of the bolt's threads are removed, clean the female thread with a tap
 
Sean titanium is a pig of a metal to drill or tap, the company you are using are probably not using the right equipment? In my experience they will need to use Carbide drills and taps, if you go down the Spak Erosion route this could prove costly as the material usually wears the electrode quicker then the snapped screws, Ask the company to try Carbide tooling, or look for a precision engineer company and ask them for there advice before putting the wheels with them, good luck mate.
A note to remember the bolt has probably worked harden as well?
 
Pingu said:
Very sharp HSS or Cobalt drill bit (you can sharpen HSS, cobalt bits are usually coated and can't be sharpened without damaging the coating)
Shortest possible drill bit length
Centre punch workpiece
Very slow drill speed (10s of rpm, rather than 100s) e.g. 4mm drill bit - use 70rpm
Lots of coolant (do not allow workpiece to show any signs of heat - if it does, you may need specialist tooling [spark erosion])
Push hard on drill bit for very short time on each "pass"
Do not allow drill bit to dull, keep drill bit very sharp (either by changing the bit or sharpening it)
Drill about 1-2mm on each "pass" and remove bit to remove swarf and allow workpiece to cool

Remove bolt threads from female thread with a pick
You won't be able to remove them with a tap without causing damage
When all traces of the bolt's threads are removed, clean the female thread with a tap
Click to expand...
I had the said bolts glowing hot at one point whilst trying to remove them, there where ten and I managed to get 5 out using this method, will this have hardened them even further
 
If you let them cool slowly and not quenched with cold water they shouldn't have hardened much Sean.

Tony.
 
They're not a very good engineering company if they can't drill out a titanium stud. Poor show.

I would personally mount it in a mill and drill it out with a carbide drill.

If they really knew their onions they could spark erode it.
 
Sean d said:
I had the said bolts glowing hot at one point whilst trying to remove them, there where ten and I managed to get 5 out using this method, will this have hardened them even further
Click to expand...

They wont harden unless they are fast quenched. Air cooling most metals takes them back to "normal" hence the term "normalising". Titanium is a hard metal so you probably haven't changed their state by drilling them to glowing hot and allowing them to air cool.

Titanium wont work harden either, that's one of the reasons it's extensively used in aerospace projects.
 
Last edited:
Sean d said:
I had the said bolts glowing hot at one point whilst trying to remove them, there where ten and I managed to get 5 out using this method, will this have hardened them even further
Click to expand...

I'd seek out an engineering company that can do spark erosion. Tell them that you have had a go already and heated the bolts already. It will save you in the long run as they will probably go straight to the spark erosion and not bother trying to drill them out.
 
Its a shame that you are to far away from Hunting Oilfield Services in Aberdeen (edit, just seen name change Hunting Energy Services) I worked for them for years over here at the Dutch facility and the lads in the work shop were always doing jobs like this in the weekends on their own and friends and family cars.
 
Sean what a shame I sold my engineering company? to a large Aerospace company? as my shopfloor worked on Titanium most days? please see Google write-up below:whistle:
upload_2018-8-27_7-44-11.webp
The heat generated by cutting tends to stay in the tool rather than transferring to the metal part — so as the tool heats up, it easily erodes and deforms. Titanium and its useful alloys tend to work-harden immediately, much like stainless steel. That can become a problem if, for example, you have to drill a deep hole.11 Oct 2013:whistle:

If you can't get this done another option is to get the rims down to me and then I will get a local company to machine them?
 
I may well just move them on, thinking of completing the fronts as the rims are done and sticking them on ebay
 
I collected the rims today and they have tried drilling all six studs and not one is central, he suggested that I cut into the side and remove the stud sideways, take them back and they would weld, drill and tap them, I took them to another place and explained what had happened, the guy had a wry smile on his face and said he could more then likely sort five of them, the sixth would be tricky as the other place had drilled about 8mm in off centre.
 
Well i guess you won't be going back to the first place then Sean.
 
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