Major Issues: Modify Cylinder head.

etd · July 22nd, 2009, 03:01

I purchased a 'Modify Enhanced Cylinder Head - V3 (Except AUG)' for my V3 sig 552 mechbox and the holes that hold it in place to the mechbox are about 1-2 mm to small. I'm wondering if this is a regular thing with modify parts or if its just my mechbox.

Amos · July 22nd, 2009, 03:37

Brand of SIG?

etd · July 22nd, 2009, 10:33

swiss arms 552 - the canadian clear version.

yuhaoyang · July 22nd, 2009, 10:49

is that the JG or something else?
It's the black mechbox one right?

Jimski · July 22nd, 2009, 11:32

I had the same problem on TMs and CAs and with systema heads.

the first thing would be to reduce the metal tits in the mechbox, but if doing so allows some movement in the cylinder head during operation, that may be another problem, am I right?

Darklen · July 22nd, 2009, 11:42

Machining the cylinder head pin openings is quite tricky. If you open them up too much, the head can twist in the cylinder. Too much twisting can bind or even break the tappet plate. Ideally, they should be drill open just a hair larger than the gearbox pins so they just fit with minimal torsional (twisting) movement. Front to back movement isn't so much of an issue as the tappet plate can only move so far forward (it hits the gearbox shell) and so far back (movement governed by the tappet nub on the sector gear).

daddy6stringer · July 22nd, 2009, 17:34

I would suggest not drilling it, unless you are absolutely sure of what you are doing. As a machinist I know all too well what can happen if your drill bit isn't right on size and location. If one cutting lip of the drill bit is even slightly different size from the other, you can run into the issues described in the previous post. Most drill bits also tend to drill a fair bit larger or smaller of their size, as well as out of round.
Although not a noticeable amount, it can make all the difference in the world.
If you are okay with doing it yourself, make sure you have the proper tools for the job, do it as accurately as you possibly can, take your time, and don't force the drill bit. Most importantly, don't run the drill press on too high of a speed. An edge finder would end up being your best bet, as the pointed end can be used to assist in locating the center position of the hole. Also, use V-blocks.

As an alternate solution, I would recommend removing material (very carefully) from the nubs that go into the cylinder head. Use some fine emery paper or whatever you have that will have a very slow material removal rate. You don't want to take off too much, or they will sit too loose. Just keep testing for a good fit.

Hope that helps...

D6S

etd · July 23rd, 2009, 02:39

Well... I'm searching for a dremel tool to help with the nubs. I've been slowly sanding them but I can't get a perfect 90 degree angle. It turns out there Cylinder head is also to far forward which means I'm going to have to shorten it too. This is becoming really complicated....

daddy6stringer · July 23rd, 2009, 09:29

Use files. It may be worth it to invest in a few Swiss Pattern Needle files for that one. A dremel tool could make a mess of things -VERY- quickly. You want the slowest material removal possible. Swiss pattern files would also allow you to get a good 90deg angle.

m102404 · July 23rd, 2009, 09:37

I've always drilled them out on a drill press. I tend to end up elongating the holes to fit and touching it up with a round needle file.

Probably not the best thing to do...but it's worked. At least on the ones I did the tits were too far forward...and it's tight getting to their front side to remove material. If I was smart I would have used emery cloth and "shoeshined" the post to fit.

Anyways...the easiest thing to do is get a different cylinder head....or a better mechbox shell.

Tys

daddy6stringer · July 23rd, 2009, 10:24

If it's worked for you in the past, then by all means...It is a good enough method.
Personally, though drill presses -can- be accurate, I find it requires a bit of setup to get it accurate to the point where I will trust it for anything but a "quick" job with loose tolerancing. That is why I have to recommend removing material from the nubs. It may be tight getting in there, but the material removal rate is slow enough such that you can accurately gauge it with the cylinder head every so often to ensure optimal fit.
Again, if it worked for you repeatedly, then it is a good method, and keep doing it. I'm a machining nerd, so I'm prone to wanting to go all out with it. But for those that aren't so inclined...slow material removal is probably the safest way. And especially considering that it's a Stainless Steel Cylinder Head, some serious problems could result from improper setup. IIRC, you're a bit of a machining type yourself, m102404, so it isn't probably that big of a deal, and you are familiar with the ins and outs of the machinery and the machinability of various materials... Etd may not be so fortunate...

coach · July 23rd, 2009, 11:05

A drill press is probably the easiest way to do it. clamp the cylinder head. use a smaller bit to get your alignment done, then increase the bit size in as small of an increment as you can. remove and test fit. if you need to elongate the holes in one direction, shift the cylinder head, repeat.

removing material from the nubs/tits will weaken it. ever so slightly but it will.

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July 22nd, 2009, 03:01	#1
etd Trader rating Join Date: May 2008 Location: North Bay, Ontario	Major Issues: Modify Cylinder head. I purchased a 'Modify Enhanced Cylinder Head - V3 (Except AUG)' for my V3 sig 552 mechbox and the holes that hold it in place to the mechbox are about 1-2 mm to small. I'm wondering if this is a regular thing with modify parts or if its just my mechbox. __________________ etd/Carmelo - Team North Bay v3 Aeg specialist

July 22nd, 2009, 03:37	#2
Amos Trader rating Join Date: Aug 2006 Location: Japan	Brand of SIG? __________________ Custom Builds: FA3674U Krinkov G3SD6

July 22nd, 2009, 10:33	#3
etd Trader rating Join Date: May 2008 Location: North Bay, Ontario	swiss arms 552 - the canadian clear version. __________________ etd/Carmelo - Team North Bay v3 Aeg specialist

July 22nd, 2009, 11:32	#5
Jimski Trader rating Join Date: Jun 2005 Location: Montreal	I had the same problem on TMs and CAs and with systema heads. the first thing would be to reduce the metal tits in the mechbox, but if doing so allows some movement in the cylinder head during operation, that may be another problem, am I right? __________________

July 22nd, 2009, 11:42	#6
Darklen Administrator Trader rating Join Date: Jan 2004 Location: Red Deer, AB	Machining the cylinder head pin openings is quite tricky. If you open them up too much, the head can twist in the cylinder. Too much twisting can bind or even break the tappet plate. Ideally, they should be drill open just a hair larger than the gearbox pins so they just fit with minimal torsional (twisting) movement. Front to back movement isn't so much of an issue as the tappet plate can only move so far forward (it hits the gearbox shell) and so far back (movement governed by the tappet nub on the sector gear). __________________ *ASC Age Verifier for Red Deer & Area Alberta*

July 22nd, 2009, 17:34	#7
daddy6stringer Trader rating Join Date: Apr 2008 Location: Espanola, Ontario	I would suggest not drilling it, unless you are absolutely sure of what you are doing. As a machinist I know all too well what can happen if your drill bit isn't right on size and location. If one cutting lip of the drill bit is even slightly different size from the other, you can run into the issues described in the previous post. Most drill bits also tend to drill a fair bit larger or smaller of their size, as well as out of round. Although not a noticeable amount, it can make all the difference in the world. If you are okay with doing it yourself, make sure you have the proper tools for the job, do it as accurately as you possibly can, take your time, and don't force the drill bit. Most importantly, don't run the drill press on too high of a speed. An edge finder would end up being your best bet, as the pointed end can be used to assist in locating the center position of the hole. Also, use V-blocks. As an alternate solution, I would recommend removing material (very carefully) from the nubs that go into the cylinder head. Use some fine emery paper or whatever you have that will have a very slow material removal rate. You don't want to take off too much, or they will sit too loose. Just keep testing for a good fit. Hope that helps... D6S __________________ A-23 Greater Sudbury Area Last edited by daddy6stringer; July 22nd, 2009 at 17:54.. Reason: provided alternate solution...

July 23rd, 2009, 02:39	#8
etd Trader rating Join Date: May 2008 Location: North Bay, Ontario	Well... I'm searching for a dremel tool to help with the nubs. I've been slowly sanding them but I can't get a perfect 90 degree angle. It turns out there Cylinder head is also to far forward which means I'm going to have to shorten it too. This is becoming really complicated.... __________________ etd/Carmelo - Team North Bay v3 Aeg specialist

July 23rd, 2009, 09:29	#9
daddy6stringer Trader rating Join Date: Apr 2008 Location: Espanola, Ontario	Use files. It may be worth it to invest in a few Swiss Pattern Needle files for that one. A dremel tool could make a mess of things -VERY- quickly. You want the slowest material removal possible. Swiss pattern files would also allow you to get a good 90deg angle. __________________ A-23 Greater Sudbury Area

July 23rd, 2009, 09:37	#10
m102404 Tys Trader rating Join Date: Apr 2006 Location: Toronto	I've always drilled them out on a drill press. I tend to end up elongating the holes to fit and touching it up with a round needle file. Probably not the best thing to do...but it's worked. At least on the ones I did the tits were too far forward...and it's tight getting to their front side to remove material. If I was smart I would have used emery cloth and "shoeshined" the post to fit. Anyways...the easiest thing to do is get a different cylinder head....or a better mechbox shell. Tys

July 23rd, 2009, 10:24	#11
daddy6stringer Trader rating Join Date: Apr 2008 Location: Espanola, Ontario	If it's worked for you in the past, then by all means...It is a good enough method. Personally, though drill presses -can- be accurate, I find it requires a bit of setup to get it accurate to the point where I will trust it for anything but a "quick" job with loose tolerancing. That is why I have to recommend removing material from the nubs. It may be tight getting in there, but the material removal rate is slow enough such that you can accurately gauge it with the cylinder head every so often to ensure optimal fit. Again, if it worked for you repeatedly, then it is a good method, and keep doing it. I'm a machining nerd, so I'm prone to wanting to go all out with it. But for those that aren't so inclined...slow material removal is probably the safest way. And especially considering that it's a Stainless Steel Cylinder Head, some serious problems could result from improper setup. IIRC, you're a bit of a machining type yourself, m102404, so it isn't probably that big of a deal, and you are familiar with the ins and outs of the machinery and the machinability of various materials... Etd may not be so fortunate... __________________ A-23 Greater Sudbury Area

July 23rd, 2009, 11:05	#12
coach aka coachster Trader rating Join Date: Mar 2008 Location: T dot	A drill press is probably the easiest way to do it. clamp the cylinder head. use a smaller bit to get your alignment done, then increase the bit size in as small of an increment as you can. remove and test fit. if you need to elongate the holes in one direction, shift the cylinder head, repeat. removing material from the nubs/tits will weaken it. ever so slightly but it will.

Major Issues: Modify Cylinder head.

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