Ground Rectangle Bars?

[eKretz]

I hadn't even noticed the amount of stock coming off, geez. I would be tempted to buy smaller stock if possible, then send the entire long bars out for blanchard grinding in bulk at the longest length they can fit on the machine, then sawing the individual pieces from the bar at only about 1/32" - 1/16" long and just doing the ends in bulk on the surface grinder a table-full at a time.

 

[wmpy]

There's a process called barmilling that this might be a good application for. Check out these guys...

http://www.ablebar.com/continuous-profile-milling/

I haven't tried it yet, but I've kept it in mind in case I found the right application. It helps that they're local.

 

[Nerdlinger]

Find someone with a surface grinder that has a great big table and have them do a whole batch at once. You can do the ends that way too, since you can put them all on the table at once they will be easy to block in so they can't tilt.

I've never used a Blanchard. In general would a surface grinder or blanchard be more-appropriate for this? We're talking 64 micro inch surface roughness. Thank you!

 

[Nerdlinger]

You might look for a shop with a large knife (industrial knives) grinder. The chuck will be around 8-10" wide and 10-18 FEET long. With a vertical head, it can skim the bars quickly.

Precision Knife Sharpening & Knife Grinding

Bill

Really interesting...and they are 15 minutes from me so I'll see what they say. Thanks!

 

[Nerdlinger]

How square is the stock and how square does it need to end up?
Flat grind in a Blanchard or SG on a chuck will make opposite sides flat to each other but not square.
We would grind side 1 on the chuck, put in a fixture to grind side 2 square, grind sides 3 and 4 on the chuck.
Bob

hmmm, I guess I'm not exactly sure how to measure squareness, but it's a standard "cold rolled" surface we are starting with and it FUNCTIONS just fine. I am just looking for a way to prep them more efficiently for vibrating/plating cosmetics. My experience with our in-house surface grinders is that they seem MUCH slower than a Blanchard would be, but maybe I am wrong OR maybe it doesn't matter if we can reliably let the SG run on it's own. Thank you!

 

[Nerdlinger]

Going from 1 x 2" down to 7/8 x 1 3/8" is a mile of stock by any method.
Agree how square, size limits, and finish size of the rectangle would be a great help.

to reduce the needed rough take might be a concern...perhaps addressed with the original stock size selection. Rapid getting down to +.020 or less
, or roughing two sides to square and size?

I apologize...the 1" x 2" size in my original post was just for reference when I wanted (and still do) to look for a service to grind/machine the exterior four sizes. I figured no one would need to know the ACTUAL size of the bars (being 7/8" X 1-3/8") We've always bought the 7/8" x 1-3/8" to minimize material waste BUT going to a more-standard 1" X 1-1/2" would certainly allow for talon-grip-type work.

I just think if there was a machine/service that you can feed a 12" bar through (and even if it only works on one side at a time you would have to feed it through four times) to get all sides skimmed it would be much more efficient than laying 65 blanks into a surface grinder or blanchard, etc. BUT if no such solution exists I think the next best way is to see if the part lends itself to being talon gripped (or similar.) Thank you!

 

[Nerdlinger]

Can you find 1" x 1 1/2" rectangle stock instead? Does that leave enough to clean up to 7/8" x 1 3/8"?

That would definitely leave enough to hold to for five sides and then flip and face mill off the extra 1/8". BUT there is also work that needs to be done on both saw-cut ends so it's getting a bit more-complicated than I am hoping for. IF I could get the bars or even saw-cut blanks efficiently skimmed then I could do a super-simple op 1 / op 2 in the Speedio and be done with it. But that is only under the hope that someone has a machine method that, when their profit is included, is cheaper than my guys reaching in and out of the mill more than I'd like. So oversize stock is definitely a good candidate if I can't find anyone does "cheap bar skimming machine work." Thank you!

 

[Nerdlinger]

I hadn't even noticed the amount of stock coming off, geez. I would be tempted to buy smaller stock if possible, then send the entire long bars out for blanchard grinding in bulk at the longest length they can fit on the machine, then sawing the individual pieces from the bar at only about 1/32" - 1/16" long and just doing the ends in bulk on the surface grinder a table-full at a time.

That was a miscommunication, we are buying 7/8" X 1-3/8" and skimming of about .005" with a face mill to clean up the surfaces. It sounds like I should contact some BG places to see what size bars they can put in there and compare it to sending them a box full of pre-cut blanks. Thanks!

 

[Nerdlinger]

Very interesting! I will contact them immediately. They are only about 1 hour away so that's a plus. Thank you!

 

[michiganbuck]

QT Op: (and skimming of about .005" with a face mill to clean up the surfaces.)
For .005 a surface grinder, for the ability of squareness and size in one shot seems a good choice.

Down grinding with a 1 1/2" wide wheel, having a diamond height-set to finish size to + .0005 so no measuring needed would be very fast. Yes, need a diamond height set for each size, and diamond left on the chuck close to the part/parts.

Down grinding is much faster than incremental cross grinding, but you need enough horsepower to keep the wheel at proper RPM for whole-wheel use. Often one may use a coarse grain wheel (46-36) that just makes surface finish spec. likely one might full-wheel grind .005 in two or 4 down passes with the right wheel.

 

[Nerdlinger]

Update - the guy Bill in PA suggested is 16 minutes from me and has (what I consider to be) an enormous surface grinder. He is going to put the entire 12’ bar on and ship em back to me ground on all four sides. We’ll see how it goes! Thank you, again!

 

[Nerdlinger]

QT Op: (and skimming of about .005" with a face mill to clean up the surfaces.)
For .005 a surface grinder, for the ability of squareness and size in one shot seems a good choice.

Down grinding with a 1 1/2" wide wheel, having a diamond height-set to finish size to + .0005 so no measuring needed would be very fast. Yes, need a diamond height set for each size, and diamond left on the chuck close to the part/parts.

Down grinding is much faster than incremental cross grinding, but you need enough horsepower to keep the wheel at proper RPM for whole-wheel use. Often one may use a coarse grain wheel (46-36) that just makes surface finish spec. likely one might full-wheel grind .005 in two or 4 down passes with the right wheel.

OH I see what you're saying...so it would be one row of parts, right? i.e. use the 1-1/2" wide wheel to do the entire 1-3/8" surface without ANY cross feeding. From there we could go back up and over to another row of parts if desired. Good idea!

 

[michiganbuck]

OH I see what you're saying...so it would be one row of parts, right? i.e. use the 1-1/2" wide wheel to do the entire 1-3/8" surface without ANY cross feeding. From there we could go back up and over to another row of parts if desired. Good idea!

Wheel wear can occur down-grinding and that is why a height-set diamond very close by is good...perhaps your wheel wears away .001 with a run of parts, so you diamond skim .001 and then just tickle the part. (10 to 30 seconds to dress). With having +- .002 or more you might dress every second or third run of parts.

Many grinder hands call down grinding plunge grinding (that is Ok)

Good to use the diamond skim dress as the size-setter so every part is in spec, with rarely checking a part for size. Perhaps the part size is .0005 dial reading lower than the dress (or what.) Perhaps check/micrometer every 100th part for diamond wear.

*Far cranking handwheels to go to the diamond is a huge time waster.

 

[boslab]

Buy a load of Indian parallels and chop them up, if you buy a quantity they’re probably cheaper, just an idea
Mark