Removing machining marks from grooves

[prophub]

Hi Guys,

I'm new to machining and have probably a question you've tackled a thousand times but for the life of me I can't come up with a simple answer. I'm building a Burr puzzle for my Dad's x-mas present. I still have some work to do with knocking down the sharp edges and corners but my question concerns the machining marks in the grooves of the blocks. How do you polish them out or at least make them less noticeable? I was thinking of using some spray adhesive to a stick some sandpaper to a piece of wood cut to the size of the groove but I'm concerned about keeping everything square. Any ideas?

Thanks for looking.

Shawn

 

[maverick]

Your sandpaper idea is not to bad, just use a very fine grit like 500. Also, you can buy very fine fingernail polishing
pads in the cosmetics section of the grocery store. Your concern about keeping the surfaces square is valid.
Just go slow and pay attention. Test fit the pieces often as they can get lose rather quickly. Your dad is a
Lucky man and will certainly enjoy the puzzle.

Regards,
Mike

 

[purpleknif]

Cool project ! Been lookin for a gift idea myself. Where'd you get the plans? Thanks.

 

[prophub]

Purpleknif - I got the plans from http://homepage.ntlworld.com/bruce.viney/Plans.html. The plans are free and most importantly, they provide the solution as well!

Mike - I am concerned about loosening the joints. I was amazed how doing the outside loosened up puzzle. I guess I'll take it really slow and definitely check the fit often. I'll probably not be able to remove them completely. This brings up another question...do you normally leave a part that's going to be polished a thou or so oversize to allow for polishing or just make them tight and loosen them up to move freely with the polishing?

Shawn

 

[portlandron]

I use a "Sanding Stick" like these:

http://www.widgetsupply.com/page/WS/CTGY/file-precision-sanding-stick

 

[Dan Rowe]

If you are looking for designs for the 6 piece burr puzzle here is a site with a design calculator and a lot if information about this class of puzzles.
http://www.research.ibm.com/BurrPuzzles/index.html

Dan

 

[tattoomike68]

A good set of jewelers files rule.

 

[kc5ezc]

If you like puzzles, try:
The puzzling world of polyhedral dissections, by Stewart Coffin.
I got the CD, but the book has eluded me. It is also on the web on
John Rausch's site under, Puzzling world. Great info for those who like to
make and give puzzles.
John Burchett
in Byng OK

 

[atheras29]

Shawn
Try one of those wheels

http://www1.mscdirect.com/cgi/NNSRI...re=ItemDetail-_-ResultListing-_-SearchResults

 

[Springbok]

Nice one Shawn your dad is a lucky one to have you please try a diamond grit file sounds expensive but in reality now very cheap the come out of Tiawan. or raid your mom's boxes I am sure you will find nail filers that will do the job.

Have a nice one

Bob

 

[Swede]

For small areas like this, I'll take some 320 silicon carbide paper and wrap it around various sized blank HSS lathe bits. You'll want to keep the edges crisp, and flat areas must remain flat, so backing paper with something hard, flat, and true is essential.

The black-colored silicon carbide paper is just about all I use anymore - it's great stuff. A drop of oil will keep the paper from loading. The only other abrasive I use to any extent are scotch-brite pads for an overall "brushed" finish on large areas.

 

[maverick]

Shawn,
I ended up making extra pieces to get one good puzzle. Make them tight or slightly oversize and polish till they
fit well. The first set I made got so loose the whole thing fell apart when handled. Just a few thousandths makes
a big difference. A slight upset of the edge with a light hammer tap can tighten a loose part.
Swede's tip of silicon carbide paper with a little oil is often used in my shop.

Regards,
Mike

 

[prophub]

Thanks for all the responses! I really appreciate the help and great ideas. A couple of things I've learned so far in my journey into machining are 1)patience...rushing will only result in a bad part and 2) you're right Mike, a thousandth of an inch makes a big difference!

Yeah, I've got a couple of "spares" from the puzzle too. The first from when one of the blocks moved in the vise when it was standing on the end and the end mill dug into the side and the other from my screw up of milling the wrong part of the block when making it fit. I was wondering why I would take a couple of thousandths off a shoulder and when I tried putting the puzzle together, it didn't seem to make a difference so a couple of more thousandths with still no change. When I finally figured it out, the part was ruined. It was late and I should have known better, but at least I learned from it.

Shawn

 

[Springbok]

Hi Shawn
I think most of us old engineers have been there mistakes wise I know been there and had the T shirt etc;
Wish we had more young people like you in this world.
Keep up the good work and have a good Christmas
From a many times over grandad

Bob

 

[deverett]

Using a backing pad to keep the abrasive paper flat is a valid point.

One thing that may have been overlooked is that when using the flat paper through the groove, it is easy rock it and round the groove. Put a piece of scrap metal with a flat edge front and back of the groove and 'file' down to the scrap. If anything rounds, it will be the scrap pieces.

Dave
The Emerald Isle

 

[prophub]

That's a good tip, Thanks Dave!

You guys have all been great. Thanks for the help. I really appreciate it!

Shawn

 

[purpleknif]

Thanks Prohub. Been a machinist for 30 years and wanted to make my boss a Christmas gift out of my home shop. He takes real good care of us every year at this time and every time I suggest we get together and get him something all I hear is " F him" So, I guess I'll do something on my own for next year.

 

[Springbok]

Purpleknif,
That is a very sad indightment of your company and it's employees. Make your boss
a puzzle as our young friend has done for his father. Present it and shame the so called colleagues
for what they are worth. Your boss wants to sack the whole dam lot and get people in who will be
interested in the company. Have done it in the past.

Regards

Bob