Well, that went well... 😭 *̶&̶@̶!̶ (expletive deleted!)

QCDvacuum · March 31, 2024, 4:51pm

Today was a nice peacful day so I thought I would change my Z Plus Z axis for the nice shiny new HDZ upgrade, preparatory to fitting a 2.2Kw spindle. I have a complete set of Carbide 3D instructions and step by step guide, telling me how to manage the change. When it came to removing the 65mm spindle mount, I found a problem. One M5 bolt holding the Makita trim router had responded to the Allen key and started to unwind.

The cap head on the second M5 bolt refused to play ball. It responded as if it were cheese and I thought I would formally round out the hexagonal space and insert a stud remover, unwind the bolt and all would be well. Not a bit of it. The cap of the cap head came free and left me with a stud to remove. My next move was to use a 4.5mm cobalt drill to remove most of the bolt. The remainder is stuck fast in the rear section of the spindle mount. There may be a possibility of removing it with a long series cobalt drill, if I can obtain one. Possibly it could be save by drilling it from the rear of the spindle mount. It would need to be accompanied by a long series M5 tap set.

I have freed the router from the spindle mount, which appears to be pretty much useless in its present state. I will continue with the disassembly process tomorrow. Being a public holiday in the UK, there is not much else I wiill be able to do.

Pictures for your amusement.

Trouble began when trying to make a unifiorm hole for the stud extractor. The M5 cap head separated itself from the bolt section.

I attempted to drill the bolt out with 4.5m cobalt drill so I could consider retapping the hole. This is the swarf from the drilled stud segment of the bolt mixed with CT90 cutting fluid.

An image of the hole (top one) after it was drilled to remove all of the stud from the front part of the spindle mount before the split.

Finally I had managed to get the router free.

The spindle mounting with the still blocked rear segment.

Cautionary tale. I have never seen a cap separate from a cap head bolt like this. Oh well… onwards and upwards!

ScottsdaleSteve · March 31, 2024, 5:00pm

Love the warning stickers on your machine!

QCDvacuum · March 31, 2024, 5:04pm

I am a supporter of AvE for my enginerding fix.
He sells a few stickers as a part of his merchandise.

Chaotica · March 31, 2024, 5:33pm

When loosening the cap head hex bolts on the mounting block, it’s a good idea to loosen each one a little bit(1/4 turn) at a time in turn to help prevent bolt siezure. And if a bolt doesn’t want to move, tightening the other one to relieve a bit of the strain enough to get it started moving can help prevent twisting heads off.
Doesn’t necessarily help if the bolt head has been strained to the point of fracture though.
Only other option I could see trying would be to quick freeze the router body to get it to contract a bit while torquing the bolt loose.

Hope you’re able to get the remaining bolt stud out!

QCDvacuum · March 31, 2024, 6:21pm

Yes, surely. I think that my cap head bolt had a weak head in some manner or another, for the cap to just twist off. I am not yet sure if the Allen key may have a part to play. These are Wera Allen keys and they have a specific profile that potentially exerts all of the force at the hexagon vertices, while avoiding the flat sides of the hexagon.

My suspicion/theory is that a weakened head may be more prone to fail where the force is exerted at the vertex of the weakened head. Perhaps a metallurgist/enginerd can comment on this aspect of Wera’s Allen key profile and relate it to a weaker cap on a bolt.

I may try and drill the remaining piece of bolt from the reverse side. OTOH, I am moving to using an 80mm spindle so probably I can save myself the expense of another spindle mount and the trouble of solving this connundrum with no real payoff value to me. .