if the hole goes thru the heatsink I ussually use a flat round puch and hammer it 
the thread usually doen't get to much damage. just repeat the tapping process after removing the tap.
If the hole is blind....
it's very dificult.
If you can drill another hole next to it.
I wasted 2 or 3 hours removing a tap from a hole. and the result was a mess. I drill 3 holes with 1mm bit beside the tap blades and try to unscrew the broken bit. It's very, very difficult.
If you break a bolt, the case is simpler then.
I use two ways: file the bolt to be flat with the heatsink, mark with a punch the center of the broken bolt and start drilling with the smallest bit you've got.
now you can use a bolt extractor OR make a tap with the bolt in
if the mark is fine centered, then all the bolt will disapear. I tried it and works (fine?)...
the thread usually doen't get to much damage. just repeat the tapping process after removing the tap.If the hole is blind....
it's very dificult.
If you can drill another hole next to it.
I wasted 2 or 3 hours removing a tap from a hole. and the result was a mess. I drill 3 holes with 1mm bit beside the tap blades and try to unscrew the broken bit. It's very, very difficult.
If you break a bolt, the case is simpler then.
I use two ways: file the bolt to be flat with the heatsink, mark with a punch the center of the broken bolt and start drilling with the smallest bit you've got.
now you can use a bolt extractor OR make a tap with the bolt in
if the mark is fine centered, then all the bolt will disapear. I tried it and works (fine?)...
Broken Tap
For me, I was able to remove one broken tap because it was not in too deep yet. I just left the other broken tap in the heatsink for those that I have a hard time removing them. I figure, if I can't remove it, it shouldn't be able to drop off all by itself and short circuiting the amp and besides if you remove it, you've got a big hole on the heatsink!
For me, I was able to remove one broken tap because it was not in too deep yet. I just left the other broken tap in the heatsink for those that I have a hard time removing them. I figure, if I can't remove it, it shouldn't be able to drop off all by itself and short circuiting the amp and besides if you remove it, you've got a big hole on the heatsink!
Re: How to tap with drill press?
If you use drill press for tapping, you will break the tap for sure, because always at certain point the resistance from material occurs and it is stronger than tap itself. That's why you need a clutch. I don't know about any attachment in the form of a clutch to a drill press. Cordless drill gun however isn't too good for drilling regular holes in aluminum, because higher speeds are preferred for small holes and stand is helpful a lot too. So you need both. Try to buy used ones. You'll have two for the price of one.
jag said:But till reading these posts I did not realize that you would need a clutch for tapping
So, is there a clutch that you can attach to the drill press? Or some other technique can be used. I don't think I want a drill press if I cannot use it for tapping as well. I guess I can make some of drill guides as shown above before returning it
If you use drill press for tapping, you will break the tap for sure, because always at certain point the resistance from material occurs and it is stronger than tap itself. That's why you need a clutch. I don't know about any attachment in the form of a clutch to a drill press. Cordless drill gun however isn't too good for drilling regular holes in aluminum, because higher speeds are preferred for small holes and stand is helpful a lot too. So you need both. Try to buy used ones. You'll have two for the price of one.
Tapping with a press drill
I've manually tapped all my heatsinks so far even though I own a drill press. Looking through machinery catalogs ( or even electronics distributors such as RS and Farnell ) I have come across 'Tapping Chucks' made by Jacobs. These will fit an ordinary drill or a drill press I believe. I'm not sure if they include a clutch. I was wondering if anyone had experience with this type of drill chuck? At 90 - 100 UK pounds they are much too expensive to try without recommendation.
James
I've manually tapped all my heatsinks so far even though I own a drill press. Looking through machinery catalogs ( or even electronics distributors such as RS and Farnell ) I have come across 'Tapping Chucks' made by Jacobs. These will fit an ordinary drill or a drill press I believe. I'm not sure if they include a clutch. I was wondering if anyone had experience with this type of drill chuck? At 90 - 100 UK pounds they are much too expensive to try without recommendation.
James
Jag
You can use your drill press to tap holes. You just have to do it with the press unplugged. Clamp your piece securly in the press, lower the bit into the hole and with your free hand turn the chuck to tapping. I use this method to turn insert nuts into wood, keeps everything straight and aligned.
Bob2
You can use your drill press to tap holes. You just have to do it with the press unplugged. Clamp your piece securly in the press, lower the bit into the hole and with your free hand turn the chuck to tapping. I use this method to turn insert nuts into wood, keeps everything straight and aligned.
Bob2
tapping, removing broken taps, etc.
Thanks for the ideas. You guys have convinced me that will have to convince my wife that I need more tools.
I've done all my tapping by hand, so I've broken a few taps in my day
I suppose leaving them in (depending on where the break is) is OK. It's just not psycologically pleasing to me to leave it there, abandoned. What I've done is, if it breaks off near the surface, to use my dremel and cut a slot in the top and used a screwdriver to remove it. A few times I've had to slice into the heatsink to get the slot in the tap segment. Ugh!
For you folks in the US and Canada, just where do you get the aluminum bars that some of you use to assemble your chassis. No Home Depot near me carries them!
Peter, you have motivated me to have another try at building a chassis and trying to make it look good. If I succeed, I'll post pictures. H@&&, maybe I'll post them even if it doesn't look good so nobody else makes my stupid mistakes :
mlloyd1
Thanks for the ideas. You guys have convinced me that will have to convince my wife that I need more tools.
I've done all my tapping by hand, so I've broken a few taps in my day
I suppose leaving them in (depending on where the break is) is OK. It's just not psycologically pleasing to me to leave it there, abandoned. What I've done is, if it breaks off near the surface, to use my dremel and cut a slot in the top and used a screwdriver to remove it. A few times I've had to slice into the heatsink to get the slot in the tap segment. Ugh!
For you folks in the US and Canada, just where do you get the aluminum bars that some of you use to assemble your chassis. No Home Depot near me carries them!
Peter, you have motivated me to have another try at building a chassis and trying to make it look good. If I succeed, I'll post pictures. H@&&, maybe I'll post them even if it doesn't look good so nobody else makes my stupid mistakes :
mlloyd1
Re: tapping, removing broken taps, etc.
HD in my area carries only some angles and flat strips. Everything more fancy I get from Metal Store. You can look for them in Yellow Pages under metals/aluminum suppliers?
mlloyd1 said:[B
For you folks in the US and Canada, just where do you get the aluminum bars that some of you use to assemble your chassis. No Home Depot near me carries them!
[/B]
HD in my area carries only some angles and flat strips. Everything more fancy I get from Metal Store. You can look for them in Yellow Pages under metals/aluminum suppliers?
Bob2,
I was not being sarcastic in the comment above, I really do like the idea. I think for aluminum it might be possible to use some small lever (or screwdriver or something) to move the chuck. I am definitely going to give it a try
You do not have to use any guides this way and maybe the chances of breaking the tap are reduced since it is always perfectly aligned.Thanks to all.
Metal Supermarkets sells aluminum sheets and other stock. Their prices seem reasonable to me. They are a lot cheaper then McMaster-Carr, which also carries all kinds of aluminum. They have a store locator on their website:
http://www.metalsupermarkets.com/
--
Brian
http://www.metalsupermarkets.com/
--
Brian
I have been to several HDs in several states and this is true for all of them. Also, looking at the amount of tools required for metal-smithing, I decided to build a chasis out of wood. Here is NP's comment in the Zen4 doc:
There are several beautiful wood chasis that I have seen in this forum as well as passdiy gallery. Whether I will be able to make one, is a different matter though
If you are tapping holes in metal the way to avoid a broken tap is to drill the correct size hole in a drill press and enter the tap square. If you dont have a drill press you will need a drill guide.
Wood is ok but won't last very long.
A lubricant is a tremendous help such as grease oil or WD40 but if you are keen you can buy proper tapping lubricant. I find WD40 as good as anything.
Getting the tap square is easy if you run a (correct size) nut up the tap first so only a small amount of tap is entering the metal, hold the nut flat down on the metal and the tap will start cutting thread square. Then you can run the nut higher or remove it. Tapping a hole not square is almost guaranteed to break the tap especially if the metal is thick. Get a nut that is a good fit on the tap not a sloppy fit. Even a wooden guide is a big help starting the tap square.
I do a lot of 1/2 inch steel tapping 3/8 to 1/2 inch bolts and made up a 1/2 inch flat steel tap guide and very carefully tapped a perfectlly square hole. I clamp this on work (after the tap is in the hole and cutting a few threads) I need to tap and because the tap made the hole there is no looseness. Once the tap is started I remove the guide so it does not get worn. I have a two hand tapping handle. You need to apply equeal pressure with both hands otherwise the tap is getting side pressure which can break it. Take a bite, feel the pressure build up then back off the tap. Take another bite then take the tap right out gently and clean it properly. Plenty of lubricant.
A tapping guide is very useful.
Wood is ok but won't last very long.
A lubricant is a tremendous help such as grease oil or WD40 but if you are keen you can buy proper tapping lubricant. I find WD40 as good as anything.
Getting the tap square is easy if you run a (correct size) nut up the tap first so only a small amount of tap is entering the metal, hold the nut flat down on the metal and the tap will start cutting thread square. Then you can run the nut higher or remove it. Tapping a hole not square is almost guaranteed to break the tap especially if the metal is thick. Get a nut that is a good fit on the tap not a sloppy fit. Even a wooden guide is a big help starting the tap square.
I do a lot of 1/2 inch steel tapping 3/8 to 1/2 inch bolts and made up a 1/2 inch flat steel tap guide and very carefully tapped a perfectlly square hole. I clamp this on work (after the tap is in the hole and cutting a few threads) I need to tap and because the tap made the hole there is no looseness. Once the tap is started I remove the guide so it does not get worn. I have a two hand tapping handle. You need to apply equeal pressure with both hands otherwise the tap is getting side pressure which can break it. Take a bite, feel the pressure build up then back off the tap. Take another bite then take the tap right out gently and clean it properly. Plenty of lubricant.
A tapping guide is very useful.
remp,
i guess, with square, you mean "perpendicular to surface/aligned with hole centerline".
Agreed
, tap has to be aligned to hole to avoid braking it. And greasing is a must
Guiding the tap is a must.
I use my drill press unplugged for getting the tap aligned, then i unlock the chuck and cut the threading ready by hand.
Or i use a tap guide similar to the one you describe.
I have rectangular alu blocks with drilled, untapped holes each having one nominal diameter of one thread size. As the teeth of the tap are biggest in diameter, i let the hole guide the tap, this is square enough, never had a broken tap with that method.
And works great when using a cordless drill.
The only broken tap ever was caused by my impatience, i skipped unlocking the chuck and cutting ready via hand. IN this case i cut a screwdriver slot with ym dremel in the broken tap.
i guess, with square, you mean "perpendicular to surface/aligned with hole centerline".
Agreed
, tap has to be aligned to hole to avoid braking it. And greasing is a must disagreed. Backing the tap means cutting the chip. The chip often is harder than the uncut material, due to cold deforming and resulting strain hardening (and, if steel is cut, it can be almost as hard as the tap). So cutting the chip is maybe no damaging the tap, but certainly damaging the threading. I recommend cutting the tap in one run.
Guiding the tap is a must.
I use my drill press unplugged for getting the tap aligned, then i unlock the chuck and cut the threading ready by hand.
Or i use a tap guide similar to the one you describe.
I have rectangular alu blocks with drilled, untapped holes each having one nominal diameter of one thread size. As the teeth of the tap are biggest in diameter, i let the hole guide the tap, this is square enough, never had a broken tap with that method.
And works great when using a cordless drill.
The only broken tap ever was caused by my impatience, i skipped unlocking the chuck and cutting ready via hand. IN this case i cut a screwdriver slot with ym dremel in the broken tap.
Dice45
Originally posted by dice45
Backing the tap means cutting the chip. The chip often is harder than the uncut material so cutting the chip is maybe no damaging the tap, but certainly damaging the threading. I recommend cutting the tap in one run.
We will have to agree to disagree on that.
In steel or aluminium I find with hand tap it works better to back off the tap.
Here is an extract from my notes tertiary education metalworking class.
As the tap cuts, it leaves a chip of metal that has been cut away. The tap has three or four "flutes" (grooves) to allow the cutaway chips to escape from the hole. If the flutes become clogged with chips, the tap will bind. It will break if forced.
The chips tend to be formed in long strips. Good tapping technique requires that you break up these strips into smaller pieces that can escape along the flutes. This is done by turning the tap backward.
The procedure is to turn the tap forward one-third to one-half turn, or until you feel increased resistance. Then turn it backward until you feel it turning more easily one-quarter to one-half turn, typically. For deep tapping,, it will usually be necessary to go part way in, then unscrew the tap entirely so that you can clean the chips out of it before continuing
Originally posted by dice45
Backing the tap means cutting the chip. The chip often is harder than the uncut material so cutting the chip is maybe no damaging the tap, but certainly damaging the threading. I recommend cutting the tap in one run.
We will have to agree to disagree on that.
In steel or aluminium I find with hand tap it works better to back off the tap.
Here is an extract from my notes tertiary education metalworking class.
As the tap cuts, it leaves a chip of metal that has been cut away. The tap has three or four "flutes" (grooves) to allow the cutaway chips to escape from the hole. If the flutes become clogged with chips, the tap will bind. It will break if forced.
The chips tend to be formed in long strips. Good tapping technique requires that you break up these strips into smaller pieces that can escape along the flutes. This is done by turning the tap backward.
The procedure is to turn the tap forward one-third to one-half turn, or until you feel increased resistance. Then turn it backward until you feel it turning more easily one-quarter to one-half turn, typically. For deep tapping,, it will usually be necessary to go part way in, then unscrew the tap entirely so that you can clean the chips out of it before continuing
Peter and remp,
there indeed are cases on has to back off, agreed.
I crosschecked with German metalworking text books, the older ones agree with your method, the newer ones second cutting in one run if possible.
BTW, i messed more than on threading up by backing off and restarting and cutting a 2nd 1st groove. My clumsiness, i guess.
I never had the tap's groove full of chips, i limit thread depth to 2.5 nominal diameters usually. Only the 1st 3 gangs of a threading are carrying anyway.
there indeed are cases on has to back off, agreed.
I crosschecked with German metalworking text books, the older ones agree with your method, the newer ones second cutting in one run if possible.
BTW, i messed more than on threading up by backing off and restarting and cutting a 2nd 1st groove. My clumsiness, i guess.
I never had the tap's groove full of chips, i limit thread depth to 2.5 nominal diameters usually. Only the 1st 3 gangs of a threading are carrying anyway.
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