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[Closed] metal machinists - top hat drilling

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[#4830148]

If you had a shock mount kit that was correct except for 6mm instead of 8mm hole - could you get the 6 drilled to 8 ? and any ideas on costs


 
Posted : 03/02/2013 7:05 pm
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Lathe and centre drill, no?


 
Posted : 03/02/2013 7:17 pm
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Lathe and boring tool - simple.


 
Posted : 03/02/2013 7:18 pm
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How concentric does the 8mm hole need to be to the outer diameter? if not much, just a hand drill will be fine. Assuming there's enough metal left after drilling to 8mm.


 
Posted : 03/02/2013 7:22 pm
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i'd try murdering it out with a hand drill. if you can bring it to my unit in essex tomorrow evening i'll bore it out on the lathe for free!


 
Posted : 03/02/2013 7:24 pm
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I've made some brass one that have lasted well over a year, just drilled and reamed.
Lathe preferred but a half decent pillar drill, adjustable table and vice could just about do it.


 
Posted : 03/02/2013 7:24 pm
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Lathe with an 8mm drill in tail stock. Drill through then de-burr with countersink on either side. Simples.


 
Posted : 03/02/2013 7:27 pm
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Why on earth would you bore it out when you can use a reamer.
Has to be concentric to the diameter that fits in the DP bush.


 
Posted : 03/02/2013 7:42 pm
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reamers are old skool.


 
Posted : 03/02/2013 7:44 pm
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So you are gonna take the time to bore out to 8.00mm where a reamer will do in one cut to size no problem and accurate.
Old skool my ar*e!


 
Posted : 03/02/2013 7:49 pm
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Why on earth would you bore it out when you can use a reamer.

It's unusual to find a reamer that'll take a 6mm hole to a 8mm hole. Reamers are normally used to make very precise diameter holes so you might drill 7.5mm and them ream to 8mm. The hole in a shock mount reducer is only a clearance hole for a screw so the precision of the diameter is unimportant, relative to the concentricity. Drilling it out with a good 8mm drill would be perfectly acceptable. No need to bore or ream.


 
Posted : 03/02/2013 7:58 pm
 cp
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willej +1


 
Posted : 03/02/2013 8:00 pm
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2mm is a bit much to ream out, I'd drill it to 7mm first. If you want a round hole use a ream, straight fluted if your hand reaming.


 
Posted : 03/02/2013 8:03 pm
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My mistake should have stated drilling out to 7.5 - 7.7mm before reaming.
Concentricity is important as both sides need to line up to allow the 8mm pin or bolt to pass through any misalignment would cause problems.
Hole drilled to big will give to much play in the mount.


 
Posted : 03/02/2013 8:03 pm
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TBF, actual concentricity isn't really an issue. The main thing is to get the hole straight. Get it in a decent lathe chuck so it runs true, nice sharp twist drill, and it will follow the existing hole.


 
Posted : 03/02/2013 8:17 pm
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Realistically though if you don't have the kit and skills to do it yourself, it's likely to be cost effective just to replace the wrong part.


 
Posted : 03/02/2013 8:18 pm
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wysiwyg - Member
Lathe and centre drill, no?

Why complicate the issue? Many moons ago, Tom Barker + drill in the Ft.William car park sorted mine


 
Posted : 03/02/2013 8:23 pm
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sounds like it'd be quicker to make a new one to me ๐Ÿ™‚

don't pass it on to bren though, he's planning on welding a reamer into it.


 
Posted : 03/02/2013 8:24 pm
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If the hole isn't straight then the concentricity will out.


 
Posted : 03/02/2013 8:29 pm
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What a tool!


 
Posted : 03/02/2013 8:30 pm
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willej - Member
Why on earth would you bore it out when you can use a reamer.
[b]It's unusual to find a reamer that'll take a 6mm hole to a 8mm hole[/b]. Reamers are normally used to make very precise diameter holes so you might drill 7.5mm and them ream to 8mm. The hole in a shock mount reducer is only a clearance hole for a screw so the precision of the diameter is unimportant, relative to the concentricity. Drilling it out with a good 8mm drill would be perfectly acceptable. No need to bore or ream.

No shit. ๐Ÿ˜†


 
Posted : 03/02/2013 8:32 pm
 kevj
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+1 for Northwind tbh, but if you are to DIY, then set it up on a pillar drill and use a 6mm bit through the bore and clamp to ensure concentricity. Swap out the bit to 8mm and drill through.


 
Posted : 03/02/2013 8:42 pm
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cheers Jamie - but in Berks, so will try to find a local chap


 
Posted : 03/02/2013 8:43 pm
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.5 of a mil is waaay too much for an 8 reamer as well. Theyre not cheap.


 
Posted : 03/02/2013 8:44 pm
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It's just a clearance hole, hand drill and 8mm bit is all you need.

All that matters is parallel faces when everything in clamped down, of which you are not effecting by doing anything with the bore (unless you make a real mess of it). Also, once everything is clamped down, it's the friction between faces that keeps everything fixed, all the bolt does is clamp everything together to achieve said friction.

Reaming? Really? There is no bore/shaft interaction here for fit.


 
Posted : 03/02/2013 8:44 pm
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Wow way to overcomplicate things - hand drill and a vice.

Anything else is just showing off.

Athough i have in the past modified a frame with a hacksaw and a facing tool to make a set of forks fit ๐Ÿ˜‰


 
Posted : 03/02/2013 8:48 pm
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.5 of a mil is waaay too much for an 8 reamer as well. Theyre not cheap.

I'm guessing you mean 0.5 of a mm. 0.5 of a mil is waay too little for a reamer ๐Ÿ˜€
But yeah 20 thou/mil / 500 microns is too much.


 
Posted : 03/02/2013 9:44 pm
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I'll do it on my lathe if you want, won't cost anything. Contact me by e-mail from my profile for adress.


 
Posted : 03/02/2013 10:49 pm
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I wouldn't want anyone drilling holes in my top hat, they'd kick me right out at the next young conservatives convention. Well, they'd kick me out anyway cus I'm an old fart. ๐Ÿ˜ฅ


 
Posted : 03/02/2013 11:10 pm
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Dont argue about it its all in here ๐Ÿ™‚

http://compare.ebay.co.uk/like/190580021532?var=lv&ltyp=AllFixedPriceItemTypes&var=sbar&cbt=y


 
Posted : 03/02/2013 11:32 pm