Enlarge hole in IRF240?

Eric · 18th January 2010, 03:04 AM

I know I've seen some discussion of this before, but I cannot find it using the forum Search.

Can I drill out the hole in an IRF240 to make it big enough to accommodate an M4 screw without damaging the transistor or should I mount them with a smaller screw?

I was planning on using M4 screws to hold the chassis together and didn't really want to play with tapping different sized holes...

Thanks,
Eric

Geek · 18th January 2010, 03:06 AM

I've drilled them 5/32 to clear #6 screw no problems

Cheers!

Conrad Hoffman · 18th January 2010, 03:52 AM

You can, but just be aware that if you warp the part by clamping it too tightly, you'll crack the silicon- a bad thing. Clamp it too loosely and you'll have it spinning about- a bad thing. Look up the torque specifications for mounting tab devices and you'll see that a large screw isn't necessary. So, proceed with caution, or tap the correct sized holes.

CH

pjp · 18th January 2010, 12:10 PM

What about the effect of vibration ?
Surely it cannot be good for the wires bonded onto the die ?

flg · 18th January 2010, 05:00 PM

What vibration? We try not to ad mechanical noise either(Vibration), do you have your electronics on the top of your sub box?
The wire bonds are "encapsulated" in plastic. They won't vibirate. Your caps are wraped plastic and foil, they potentially are subject to vibration.

BTW, I have also enlarged the TO-247 pkg holes to #6 (USA) screws 100's of times without any problem. I like #6 screws better but, be aware of torque specs and use a big or springy washer or both. Nelson has had good luck with clip hold-downs also.

Eric · 19th January 2010, 06:20 PM

Thanks for all of the input! I appreciate it very much!

Eric

tiefbassuebertr · 19th January 2010, 07:15 PM

Quote:

Originally Posted by Eric

I know I've seen some discussion of this before, but I cannot find it using the forum Search.

Can I drill out the hole in an IRF240 to make it big enough to accommodate an M4 screw without damaging the transistor or should I mount them with a smaller screw?

I was planning on using M4 screws to hold the chassis together and didn't really want to play with tapping different sized holes...

Thanks,
Eric

I have do this with help of a engineers respective maintenance file set (round styles). A good choice is the brand BAHCO.
Bahco – True professionals’ love for increasing their performance by its ergonomics and design

Magura · 19th January 2010, 07:26 PM

The idea to use a file, is sure good.

To recommend Bacho is however not. They charge the same as Pferd, but the quality of Pferd files is quite a bit better.

PFERD Needle Files

Magura

Eric · 20th January 2010, 12:27 PM

Another excellent suggestion - Thanks!

Eric

AndrewT · 20th January 2010, 12:43 PM

the To247 has a 3.1mm to 3.5mm diam hole. It is tapered
I have drilled many of these to 3.5mm for M3.5 mounting screws.
The plastic on the back face often breaks away leaving a small circular indent around the enlarged hole. I see no problem with this M3.5 mounting.

I have drilled a few To264 to 4mm, but I was a bit wary of this modification.
Experiment on a few damaged ones first.

18th January 2010, 03:04 AM	#1
Eric diyAudio Member Join Date: Nov 2000 Location: Central PA, USA	Enlarge hole in IRF240? I know I've seen some discussion of this before, but I cannot find it using the forum Search. Can I drill out the hole in an IRF240 to make it big enough to accommodate an M4 screw without damaging the transistor or should I mount them with a smaller screw? I was planning on using M4 screws to hold the chassis together and didn't really want to play with tapping different sized holes... Thanks, Eric

18th January 2010, 03:52 AM	#3
Conrad Hoffman diyAudio Member Join Date: Mar 2007 Location: Canandaigua, NY USA	You can, but just be aware that if you warp the part by clamping it too tightly, you'll crack the silicon- a bad thing. Clamp it too loosely and you'll have it spinning about- a bad thing. Look up the torque specifications for mounting tab devices and you'll see that a large screw isn't necessary. So, proceed with caution, or tap the correct sized holes. CH __________________ I used to be an audiophool like you but then I took an arrow to the knee.

18th January 2010, 05:00 PM	#5
flg diyAudio Member Join Date: Jul 2005 Location: North East	What vibration? We try not to ad mechanical noise either(Vibration), do you have your electronics on the top of your sub box? The wire bonds are "encapsulated" in plastic. They won't vibirate. Your caps are wraped plastic and foil, they potentially are subject to vibration. BTW, I have also enlarged the TO-247 pkg holes to #6 (USA) screws 100's of times without any problem. I like #6 screws better but, be aware of torque specs and use a big or springy washer or both. Nelson has had good luck with clip hold-downs also. __________________ “Be who you are and say what you feel because those who mind don't matter and those who matter don't mind.” Dr. Seuss

19th January 2010, 07:26 PM	#8
Magura diyAudio Member Join Date: Oct 2003 Location: Denmark, Viborg	The idea to use a file, is sure good. To recommend Bacho is however not. They charge the same as Pferd, but the quality of Pferd files is quite a bit better. PFERD Needle Files Magura __________________ Everything is possible....to do the impossible just takes a little while longer. www.class-a-labs.com

20th January 2010, 12:43 PM	#10
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	the To247 has a 3.1mm to 3.5mm diam hole. It is tapered I have drilled many of these to 3.5mm for M3.5 mounting screws. The plastic on the back face often breaks away leaving a small circular indent around the enlarged hole. I see no problem with this M3.5 mounting. I have drilled a few To264 to 4mm, but I was a bit wary of this modification. Experiment on a few damaged ones first. __________________ regards Andrew T.


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18th January 2010, 03:06 AM	#2
Geek diyAudio Member Join Date: Sep 2004	I've drilled them 5/32 to clear #6 screw no problems Cheers!

18th January 2010, 12:10 PM	#4
pjp diyAudio Member Join Date: Nov 2006 Location: under the rainclouds	What about the effect of vibration ? Surely it cannot be good for the wires bonded onto the die ?

19th January 2010, 06:20 PM	#6
Eric diyAudio Member Join Date: Nov 2000 Location: Central PA, USA	Thanks for all of the input! I appreciate it very much! Eric

20th January 2010, 12:27 PM	#9
Eric diyAudio Member Join Date: Nov 2000 Location: Central PA, USA	Another excellent suggestion - Thanks! Eric

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