Drilling holes in head cab for chassis mounting

[xtian]

Any tips for locating the holes to mount the chassis to the head cab?

[xtian]

Not sure I have the tools to do this, but I was thinking I could sharpen to points the ends of the mounting bolts, reverse them and screw them into the chassis, so that the points are just barely sticking out from the bottom of the chassis, then place the chassis in the head cab, and push down to indent the wood with the pointed bolts.

Any simpler ideas? Careful measurements with my digital caliper?

[Gibsonman63]

The last one that I did, I made a template out of posterboard that matched the chassis... and rechecked my measurements about four times.

[LarryLarry]

I did a combination on my latest cabinet. I used the chassis bolts to hold the feet as well. I made a cardboard template with the cabinet facing bottom up, template on the outside. Then I put the back 2 bolts in the chassis in reverse and rubbed some graphite on them. I put the chassis in while keeping the back screws from scraping as best I could. When I got the chassis positioned correctly I pushed down on it to make marks on the inside bottom of the cabinet.

I then took out the chassis and measured one of the bolt marks from the back and from the side. I turned the cabinet upside down again and marked the hole from my measurements. (checked them many times before drilling). After that hole was drilled I put the template on and lined up the one hole I drilled. I then marked and drilled the other back hole.

Then I put the chassis back in and made sure the back bolts fit correctly. I pulled the chassis, put the template back on and marked the 2 front holes.

Worked great - just measure measure measure!

[billyz]

Not sure I have the tools to do this, but I was thinking I could sharpen to points the ends of the mounting bolts, reverse them and screw them into the chassis, so that the points are just barely sticking out from the bottom of the chassis, then place the chassis in the head cab, and push down to indent the wood with the pointed bolts.

Any simpler ideas? Careful measurements with my digital caliper?

I do it the same way. I have made templates too, but I never seem to get them just right.

[Big Jim]

All of this has got me thinking...this could be dangerous. I remember installing my Express into its cab was kind of a pain. I am in the process of getting a chassis ready for an upcoming Rocket build. The chassis started as a blank from Watts tube audio. I bought it with the bottom plate that has holes pre punched where the mounting lugs are. I might actually build the cabinet first, use the bottom plate as my template, and kind of back door approach this build. Sure would be easier it seems. Wouldn't be faced with fitting finished stuff together. Food for thought anyway.

[M Fowler]

If I order a Watt's chassis I order the bottom plate and mark the size on it for future reference as my hole drill guide. I have one for each type of Watt's chassis I use.

Otherwise I use hard card, trace the chassis, mark the holes, punch out holes and mark the head cab for drilling. Allow for face plate spacing. The Dumble chassis are the hardest I think to get this right.

Mark

[Big Jim]

Ordered my figured Cherry today. I'm starting to get excited about this build.

[sliberty]

No matter how you mark the position of the holes, drill them oversized. This will give you some wiggle room to align the faceplate properly even if you were slightly off in your markings. The larger hole will either be covered by the feet, or if you are not mounting the feet in those holes, you can use a large washer to cover the larger hole.

[xtian]

No matter how you mark the position of the holes, drill them oversized.

And we have a winner!

[amplifiednation]

Not sure I have the tools to do this, but I was thinking I could sharpen to points the ends of the mounting bolts, reverse them and screw them into the chassis, so that the points are just barely sticking out from the bottom of the chassis, then place the chassis in the head cab, and push down to indent the wood with the pointed bolts.

Any simpler ideas? Careful measurements with my digital caliper?

This is the best way. If you have 1/8" or 1/4" ply you can make a jig that you can test on the chassis first, then transfer the holes. Mounting holes are more threatening than they are difficult. If you don't have the tools to make those punches, you can use posterboard as suggested, then even the flat bolts will mark the paper in the right spot.

Always drill oversized, even as big as 7/16

[DaveMon]

Sharpening bolts sounds labor intensive.....I have a "quick and dirty" alternative borrowed from my days of assembling F-16 aircraft... if you can place a dab of a marker substance on each bolt end...i.e solder flux, white lithium grease, or a tiny amount of something you will be able to spot...you can carefully "mate" the parts together, seperate and locate the holes on the spots of marker goop.

Before everyone screams at me..... only use a TINY amount of marking goop, and choose something that can be easily cleaned up. Also this can be done one hole at a time to be even more accurate.

I had great sucess using this method on a Superlead build where I had to locate the turretboard. I also did not need oversize holes.... just dabbed a little solder flux on the standoff posts...carefully set the turretboard where i wanted....checked and re-checked....drilled it

hope this helps....

[M Fowler]

DaveMon,

I learned that in my mechanic days but it's really difficult doing that inside a cabinet.

Mark

[Gaz]

So that's how they build F16s...

[Distortion]

Every time I build a cabinet for a new style amp I make a plexiglass template for it. I personally use 1/4" plexiglass, but thinner material will work.
The template is cut to exactly the same size as the chassis. I then mount the plexiglass to the bottom side of the chassis. Have it fit as exact as possible. Once you have this done you can place a mark on the plexiglass directly over the chassis bolt hole. Try to make the mark directly in the center of the hole and make the mark small. I use a black sharpie to do this.
Next I use my drill press to drill a 1/16" hole in the plexiglass. The smaller the drill bit the more accurate you can be when are getting ready to drill the holes in the cab.
Once you have the template done, mark it so you know what amp it is used for.
Just center the template on the bottom of the cab and measure back the appropriate distance from the front. Get everything accurate, clamp the template down to the cab and then I use the same 1/16" drill bit to make the indentations in the cab. Once this is done, pull the template off and drill the appropriate size holes.
This way takes a bit to get set up right, but it will allow consistent markings for the holes.
I tried the sharp bolt trick but it was more of a pain than it was worth. Plus unless you have a very small right angle drill it is close to impossible to drill the holes from the inside.
It takes me about 5 minites to do the layout on a cab and drill the holes.