Anyone got any tips for removing low profile screws where the Allen recess has rounded? I need to replace a bearing on my leadscrew and can't get the end plate off. I've tried a star bit driver (made it worse) and a screw extractor (recess not deep enough) I'm putting off drilling into the screw head until I really have to. (Will be replacing with button head stainless when I get it out) Alex.
Alex, Dremal cutoff disk and grind a slot for a screwdriver, is pretty standard.. if you used loctite put some heat to it. Cheers Gary
yep, dremel with cutoff disk is what I would do, make a big enough slot for a decent flat screwdriver. should you not have a dremel yet, go online and order one now (-: , while you wait for it to arrive you can superglue a similar flathead bolt to the head of this one and get a grip on it with waterpump pliers or Vicegrips. remember to degrease both heads before you glue.
Thanks @Gary Caruso, @David the swarfer, good tips - I will go with the screwdriver slot as the other seven screws were really tight and I suspect superglue trick wouldn't resist the torque needed. Next job will be replacing all screws that don't need to be low profile with stainless button head.
Your Hex Tool may also need to be ground back as after using they also wear down not engaging in the low profile screws causing rounding off issue. Joe
Thanks for the input guys! Got it out with a screw extractor eventually - combined with a couple of sharp taps with a hammer to break the seal cause by the aluminium oxidising next to a ferrous screw. (I'm calling it ferrous - it is magnetic but if it's steel it's the softest I've ever come across) - Now to replace all the other screws that don't need to be low profile with stainless. Alex.
Yes - Rockwell B about the same as mild steel - 70 ish - these low profile screws still seem even softer, and the stainless means a bit less interaction with the aluminium. Alex.
Yeah, I have a couple that are stuck, too. In a couple of cases I've replaced the low profile ones with screws that take a bigger hex drive - more engagement. The little (2.5mm?) ones - hex keys AND screws - round over so easily. Would rather lose the key than the screw. Any recommendations on harder steel screws? I'd like to get a batch of them and do a wholesale replacement when I do my next periodic maintenance session.
I'm in the UK @phil from seattle, so I can't give a specific supplier. I'm using button (Allen recess) head stainless screws to replace the low profile screws that go into aluminium extrusions. The problem is two different metals, with moisture between them = battery = surface corrosion between them. Aluminium oxide swells so it grips tighter. Stainless reacts with aluminium a bit less than mild steel. I don't think I have come across any bolts or machine screws as soft as those low profile ones. Alex.
Where did you get this from? I only remember two things from Materials class thirty-some years ago and one of them was how damaging aluminum is to stainless steel.
Personal experience rather than theory @Rick2. I've assembled a lot of aluminium greenhouses over the years (and taken them apart to move them) Aluminium fixings weld themselves to the frame, mild steel corrodes badly and stainless has given me very little trouble. Admittedly there is a lot more water involved in a greenhouse than with a cnc machine lol so corrosion problems will be worse. The low profile screws I took out today were all a lot tighter than when I put them in a year ago. Alex.
Thanks for reminding me about those black oxide screws in aluminum, Alex. I have had problems with that combination freezing in the past. I think I'll back some of those out while they are still fresh and use a lubricant on the threads.
I (genuinely) don't know whether lubricant is a good idea or not - I've avoided it as I don't want anything vibrating loose. Perhaps someone else will chip in with an opinion. Alex.
