Granite Surface Plate

[Deanimator]

Can you post a readable version of the drawing?

It's pretty simple:

[ChrisR]

May have been thought about, but...

Tolerances - they'll need to know how accurate you need it. If you mean 3/8" clearance holes, better say it, else they might be tight.

I guess it doesn't matter here but if you want the centerline holes equally spaced, measure them from one end - the "datum".

Would some spare holes be useful, for mounting things later? It would be much easier to have them done now.

Do you want them to "Break all sharp edges"? Otherwise things can be surprisingly sharp.

[Deanimator]

May have been thought about, but...

Tolerances - they'll need to know how accurate you need it. If you mean 3/8" clearance holes, better say it, else they might be tight.

I guess it doesn't matter here but if you want the centerline holes equally spaced, measure them from one end - the "datum".

Would some spare holes be useful, for mounting things later? It would be much easier to have them done now.

Do you want them to "Break all sharp edges"? Otherwise things can be surprisingly sharp.

Thanks for the suggestions.

The only major metal work I'm at all familiar with is rail car parts. I used to work for a company which imported them from India and China. Our stuff was sourced to a specific customer spec, and as I recall, the sharp edges were broken during manufacturing. It's something I had vaguely considered, but thanks for explicitly mentioning it.

I hope to get a reply from the machinist tomorrow, and will address some of these issues with him.

I'll make clear that the 3/8" holes are for bolting a structure to the top and a 3/8" bolt needs to be able to pass through them.

Where and what size additional holes would you recommend? I've got enough space on the plate for magnets, and plain weighted bases, plus I have rails along the sides of the table on which studio lamps are mounted on articulated microphone arms. I'm probably good for lighting of all types, unless I want to be able to mount flashes on magic arms on the plate itself, in which case I'll either need magnetic bases for my magic arms, or to mount them to the 80/20 profile somehow.

I raised the issue of handles in my email, but I presume he was waiting for the drawing before addressing specifics. I presume he won't see it until tomorrow morning, since it was sent after normal business hours at the end of the week. Do you have any suggestions regarding handles? Industrial supply places like McMaster-Carr sell steel through bolted handles that could be used.

Again, thanks for your suggestions which are more than welcome.

[Deanimator]

I just replaced the free DoubleCAD with TurboCAD Deluxe 2018, so I should get better drawings if required. This will take some getting used to as I'm used to using Corel Draw and AutoCAD 12 for DOS. It took me several days to try to figure out how to set the origin/reference point to what I wanted it to be, making accurate placement VERY difficult.

[Deanimator]

I got the 80/20 stuff today. It looks pretty good.

I somehow managed to forget the brake handle for the linear bearing, so I ordered one from Amazon. I ordered another 40x40 profile from Amazon yesterday.

I haven't heard back from the machinist yet. I'm going to send him an email after I finish this post and mention breaking any sharp edges as was helpfully suggested yesterday.

[ChrisR]

I was just "musing" about holes being harder to add later.

I dunno - for light perhaps?
It's true that magnetic bases are very good, but something like an x-y stage wouldn't easily use those.

A line of 1/4" by 20tpi holes maybe? Or M6 - most things are metric over here.

[Deanimator]

I was just "musing" about holes being harder to add later.

I dunno - for light perhaps?
It's true that magnetic bases are very good, but something like an x-y stage wouldn't easily use those.

A line of 1/4" by 20tpi holes maybe? Or M6 - most things are metric over here.

1/4"-20 would be more useful, at least for mounting things off of the profile.

Where would you suggest the holes? Down both sides, lengthwise?

[ChrisR]

Everyone would have their own preference - you could have tapped holes, or more clearance holes...

But if you put in a lot at he same time they're cheaper

(wholesale) ...sorry.

[Deanimator]

Everyone would have their own preference - you could have tapped holes, or more clearance holes...

But if you put in a lot at he same time they're cheaper

(wholesale) ...sorry.

Having the profile in hand now, I discovered that 3/8" bolts cannot be used to fasten it horizontally to the plate, so it looks like I'll need M8s for the center hole and one end instead. The 3/8" for vertical mounting should be just fine.

I haven't heard from the machinist yet, so things are pretty much wide open.

[Deanimator]

I've now got all of the 80/20 stuff except the small linear bearing. I somehow managed to order a 10 series instead of a 40. That's going back and I've already ordered the replacement.

The real fly in the ointment is that I haven't heard from the machinist and I pick up the plate on Monday. My backup of a friend with machinist experience seems to suddenly be unreachable by phone or email (mailbox full).

My fallback fallback is borrowing an angle grinder and a hand drill guide from a friend. Definitely not the way I want to go.

[Chris S.]

Deanimator,

One tip that may expand your choices is to look for a welder/fabricator instead of a machinist. Your plate doesn't require a lathe, mill, or other specialized and expensive equipment that a machine shop has. A welder/fabricator will likely have a shear, drill press, taps, and grinder--all that's needed for your plate. Welder/fabricators may be more abundant and likely have less overhead than machinists, and therefore be more willing to take on a small job like yours.

--Chris S.

[Deanimator]

Deanimator,

One tip that may expand your choices is to look for a welder/fabricator instead of a machinist. Your plate doesn't require a lathe, mill, or other specialized and expensive equipment that a machine shop has. A welder/fabricator will likely have a shear, drill press, taps, and grinder--all that's needed for your plate. Welder/fabricators may be more abundant and likely have less overhead than machinists, and therefore be more willing to take on a small job like yours.

--Chris S.

Thanks. If there's no progress I'll give that a try.

[Deanimator]

I just confirmed the grinding, drilling and welding.

I pick the plate up Monday and drop it off at the fabricator's.

I should have it back in a week and hopefully be able to paint it in a friend's garage.

[Deanimator]

I picked up the plate today. It's every bit of 100lb.. I don't think a Panzerfaust could cause it to vibrate.

When I went to drop it off at the fabricator he was AWOL. Can't reach him by phone.

Looks like I"ll be doing all of the fabricating myself.

The handles will now have to be bolted on instead of welded.

[Deanimator]

Having been forced by circumstances to become my own fabricator, I've assembled what I think I'll need to get the job done, including an angle grinder and a vertical drill guide.

The only significant change is that due to a lack of capability, the handles will be bolted on instead of welded. I'll be using stainless steel marine hardware. I'm also adding an extra hole for an M8 screw to hold down the horizontal profile, for a total of three. Between those and the attachment to the bolted on vertical profile, the whole thing ought to be very rigid.

I won't be able to do anything before Sunday afternoon, and possibly Monday.