How much time to file down bolts ?

[MathWizard]

I need to lower a CPU mounting bracket by about 0.7mm, and it sits on special bolts, that I would just have to file down. They are just some cheap steel, and only about 8-10mm in diameter.

I have hand files, and a belt-sander here (w/ sandpaper for wood tho),

So just off the top of someones head, how long would it take by hand file, to file down 0.7mm off a 1cm dia. bolt, an hour, many hours  ? And there's 4 of them. Wish I  knew someone with a lathe. And I'm not paying $80/hour tho.

I have a rough sharpening stones too, if the bolts are just mild steel, it shouldn't be too bad.

[Someone]

With a belt sander? minutes each, the skill is not taking off too much!

... having done various mods on cooling systems in PCs to fit "odd" CPUs where they were never intended. Shimming is often easier.

[nctnico]

Taking 0.7mm off is a matter of minutes with a suitable file. Typing your post likely has taken longer.

[jpanhalt]

Are you asking about filing the head or threaded portion? 

Let's assume you mean threaded portion.  If so, be sure to put a nut on the thread above or at where you want to end filing.  Then, when done filing, remove the nut.  It will help dress the thread at the end so it can be reinserted more easily.  I also do a little hand dressing for a really smooth reattachment.

[Ian.M]

Assuming a sharp full sized fine cut file, with a good handle, (and not made of Chinesium), and the work rigidly clamped in a bench vice, you should be able to take off most of that 0.7mm in a few minutes each.  Note this assumes ordinary mild steel or medium carbon steel bolts, not above bolt grade 5, and not specially hardened.  Any alloy steel of high hardness or with a tendency to work harden would be *MUCH* slower.

A bigger problem is getting the filed down ends uniform and square.  Measure often, and change your tactics when you've taken off 0.6mm on the low side. Mark the low spots with a marker pen then file the rest down to match, again checking the measurements frequently to avoid going too far.  Ideally you should have around 0.05mm left to remove over the whole end of the bolt.   Then you need to mount the bolts to a convenient sized flat plate in a square, and lap their ends all together to get them square and down to final length.  Wet lapping with ascending number grits of Wet & Dry paper face up on a hard very flat surface (e.g. float glass on some sort of backing board) is probably the best way to go here.  Again measure often and once it stops rocking, concentrate pressure on the highest corner or side, to take those bolts down faster to get them level.  Finally, remove them from the plate and 'break' the edges or chamfer the last turn of the thread.

[MathWizard]

Ok so I should try it on a similar one 1st.
It's the bolt/spacer thing between the plates here. Yeah the flat bottom face.
http://www.thermalright.com/product/lga1700-b2-2/
In 1 picture there they look like they have a washer under, but mine don't.

If I mess it up and they aren't level, well I'll have to make my own bolt/washer/nut thing. With my sharpening  stones though, I should do ok for that if I don't go over.

[NiHaoMike]

If you have a lot to modify, it would be well worth investing in a grinder and making a jig to easily trim each bolt to the right length.

[AndyBeez]

If the bolts can be removed, for accuracy, use a lathe. Setup time 3 minutes, trimming time 3 seconds.But for just 0.7mm can you shim the back of the bolt, or any other part of the assembly, with a paper thin washer instead?

Just keep the fillings away from your cpu/mobo.

[Gregg]

Assuming you want to take some material off the knurled part opposite the threaded stud:
Using a lathe is the best way to make them perfect.
Alternately threading a block of metal so that you can screw the threaded part into the block to hold it and use a milling machine to cut off the excess.
For the home gamer, you may be able to force thread into a block of hard wood to hold the fastener, stack some washers over the outside of the knurled section to both help guide your file flat and to indicate the limit of filing.  Then use a caliper all around to determine how parallel the newly filed face is to the base and tweek them all to the same thickness.  It will take patience and a good file.

[Domagoj T]

A decent, sharp file will make a short work of if. Bolts you're likely to find in electronics are not high quality hard/tough steel, they're as soft as they go. However, a dull file will make you miserable.
That being said, by far the most important thing is workholding. Put the bolt in a vise (sandwich it between some soft material like aluminum or plastic plate or similar, to avoid damaging the thread), it will make your life much easier.

[Ian.M]

Yes, a crappy file will lead to nothing but pain and misery.  If you aren't certain your file is sharp, free cutting and large enough, go out and buy a good one.

I'd drill a hole in a small block of wood, a bit undersize for the thread, split the block of wood across the hole then put the block in the vice clamping the bolt firmly between the two halves.  It gives a lot better lateral rigidity than simply clamping between plain aluminum or plastic soft-jaws, so lets you vary the direction of filing with less chance of rocking the work.   V-grooved soft-jaws are a different mater, as they will clamp a thread (or other round object) securely, provided the V width & depth is appropriate for the thread diameter.

[coppercone2]

well this shortens bolts pretty good



24 seconds / inch or so.

[Gyro]

So just off the top of someones head, how long would it take by hand file, to file down 0.7mm off a 1cm dia. bolt, an hour, many hours  ? And there's 4 of them. Wish I  knew someone with a lathe. And I'm not paying $80/hour tho.

Just curious as 24 hours have elapsed. Have you managed to file away the total of 2.8mm yet? 

[Ian.M]

By now, he's probably worn a 1mm deep groove in a crappy Chinesium file while removing a small fraction of a mm from each screw!

[BrokenYugo]

Chuck in a drill press or hand drill in a vise, running at a fairly low speed, then go at it with a file or grinder or whatever. Work slowly and measure often.