QR/head mismatch diameter: how to match ?

[QT Luong]

In my quest to find a better ultra-lightweight ballhead than my current
Slik standard, I bought a magnesium Velbon PH-263 based on Kerry's recommendation. It is lighter than a Slik, and appears to be as strong.



What I am trying to do is to replace the stock mounting
assembly with an Arca-style quick release platform. I have a QR2 from Kirk that has
a standard 1/4 threaded hole. Problem is that after I remove the stock platform,
I am left with a screw stud that is not 1/4, but is slightly smaller. There appears
no easy way to change that screw. So how do I matte that screw and the QR2
platform, possibly in a non-permanent way ?
I have asked Kirk to make a custom QR2 with the appropriate thread size, but he has declined.

[Steve Hamley]

QT,

Cut a 1/4" bolt to the length needed to plug the hole in the Kirk plate and Loctite it in place. Loctite will break down when heated so it's removable (cut a screwdriver slot in the end before Loctiting). Drill and tap to the Velbon stud size. You can probably do either of these yourself, but the drilling should be done on a drill press to make sure the plate is square with the ball head stud. You could also have a machine shop make the reducing bushing, and I doubt they'd charge much for something that simple. It would be like a 3/8 to 1/4 inch bushing for a camera bed plate with a screwdriver slot.

A second option might be to use the right size Helicoil insert by drilling out the existing Kirk 1/4 inch hole. Easier to do by yourself with hand tools, but less reversable.

Thanks!

Steve

[Michael Mutmansky]

QTL,

Steve has two good options. One warning, though. If you try to drill out a steel plug that is mounted and frozen in aluminum, you'd better make sure that the hole you are drilling isn't too large, or it'll shread the plug, and the aluminum will get trashed due to the much softer nature of the aluminum. Make sure you are also drilling the hole in the exact center of the plug.

I think a better approach will be to use the helical adapters that he mentions. These are available many places, including mcmaster.com.

You might be able to convince Kirk to sell you one that has not been drilled or tapped. That would be the best, as you could then have a local machine shop drill and tap it the correct size for you.

They used to be willing to do custom orders, so I am suprised that they were unwilling to do this for you.

Other than those options, you could have a small piece of aluminum bolted to the bottom of the QR2 with small countersunk machine screws, and have the correct size hole drilled and tapped in that. This would involve adding a few small holes on the bottom of the QR2 in the corners, but it would leave the existing 1/4-20 hole intact so that you can use it later for another use.

---Michael

[Bob Eskridge]

Here's an elegant suggestion. First of all find out what size the stud on the Velbon is. Probably a Metric M6 X 1.0 (which is slightly smaller than the 1/4-20 size) but you can check that by going to a hard ware store and trying some metric nuts for fit.

Have a machine shop drill and tap the 1/4" hole to 3/8" X 16. Then have an M6 to 3/8" adapter insert made. Or with the appropriate drill press and taps and dies you can do it yourself.

[Bruce Watson]

All good suggestions. I had a similar problem using an Arca-Swiss B1 with my Toho. Mounting an Arca style quick release plate on a Toho is a trip. I tried to modify a plate from Really Right Stuff, but in the end made up a new drawing and had a local machine shop make one for me. They hogged it out in a hurry (I told them it didn't have to be pretty), metric threads and all. Cost me about the same as the Really Right Stuff plate.

We have these problems in the USA because we are the last country in the world that isn't metric, I think. Certainly the last of the "advanced" countries still clinging to imperial units. Really makes you wish that Reagan had kept his promise and taken the country metric doesn't it? Sigh... Yet another meaningless hassle (YAM'H, say it like a Klingon, two sylables with the emphasis on the last one, and a sneer ;-).

[Richard Martel]

QT...There is a company called Devcom (devcom.com). They have epoxy based metal puttys. Look under repairing holes. These products have a hi tensile sstrength and may solve your problem....Good luck and thanks for all of the help you have given to me and others ...Regards, Richard

[Richard Martel]

QT...I should have added that you would fill the hole with their stainless steel or aluminum putty, let it cure then drill and tap the plate. Srew on the head then apply force with your hands to attempt to "fail" the repair if it passes the test I would use it with confidence...R

[Matt Long]

QT:

Here is another option: I had a small Giottos ball head that had the stud machined from the stem of the ball assembly. This stud had twisted off (no surprise, considering that it was cut from cast aluminum) and I was left with no other option that to drill a new hole in the center of the ball stem and tap it to 1/4-20. I then secured a steel stud into the stem with Loctite (red) and then used a 1/4-3/8 bushing to mate to my RRS quick release plate.

If the stud on your Velbon is cast into the ball assembly, you can grind it off (if you're feeling adventurous) and drill and tap the stem to 1/4-20. It isn't as difficult as it may seem, provided that you use a drill press. If the metric stud on the Velbon is threaded into the ball stem, you may be able to remove the stud after applying some heat directly to the base of the stud/ball assembly joint.

The other option, which is probably the simplest, is to bring the ball head to a machine shop and have them do the job for you. To quote the owner of our local machine shop, (who is also a die hard Harley-Davidson and Studebaker fan): "Regardless of your passion, you've got to customize your toys."

Happy customizing!