I’m started a big production run of samples and will have many, many, many
sprues to get rid of. Can anyone recommend flex shaft wheels or burs they
like that make sprue-removal and filing faster? I’ve always just sawed and
filed, and am not sure if silicon carbide wheels or Rex-Cut wheels are even
appropriate for the job?
Thanks in advance for any recommendations!
I suggest contacting the Platinum sponsoring tool-suppliers on Ganoksin. There’s ‘so much of a wealth of help’ with them. Hope this helps you!
I’m Gerry, On my iPhone!
I use the Dremel (maybe someone else makes them too) fiberglass cutting
wheels. They are super strong and don’t break like the oxide wheels (they
are a bit thicker though). Then I use a Heatless Mizzy wheel to grind off
the little stub that’s left after cutting.
large heavy sharp side cutters. Snip Snip Snip
Casting houses do most of that on polishing motors. Use 6” diameter 3/4” wide cratex type wheels for the sprues, then diagonal laps for the sides. They use fancy hydraulic sprue cutters to clip them off.
So you can send them to a casting house and get them 95% finished. They will not be a beautifully shaped as they would if you did them yourself. Send a couple test ones first to see if it’s good enough.
I’d buy a sprue cutter if you don’t have one. There’s all different kinds. Hand held or bench mounted. I’d still file the sprues off with a big file, cut 0. There are some really nice carbide barrel type cutting burs but those really can grab and trash your shank if you use them on the outside. If you want to use an abrasive wheel for sprue removal you’d need a really hard one because otherwise it will constantly deform. Those big cratex wheels the casting house used were really hard and the rings got super hot. If doing by hand I’d file, emery, rubber wheel the outside. Then ream the inside with a carbide barrel bur. Then tumble. Then go over them again. Prepolish where setting, then set, then final polishing. Lots of work for sure.
Some just wheel off the sprue and parting lines and tumble like crazy. It works but looks like a half melted Jolly Rancher.
I remove most of my own sprues with a flex shaft as well (I don’t have a polishing motor). If they are on a flat and easily accessible area, I start by sawing them close, then from there I use snap-on flat sanding discs through various grits (EC Moore brand). I have tried many bits and tools, and have found this to work the best for my own particular castings.
If it’s in an area that isn’t flat or easily accessible, I try to come in at an angle with a cutting wheel if I can, just to get it started. Kind of like how you see people cut down trees. If I can’t get an angle to cut it all the way through, even the notch helps significantly. Then I go in with an aggressive carbide barrel-shaped burr and lots of Burr Life lube. I know this isn’t usually recommended, but it works fast. I do protect my fingers with leather cots, as if they catch your skin it hurts. (It can also really mangle your piece depending how delicate it is and how steady your hand is.) After that, I follow up with the above sanding discs which are quite flexible, but if they won’t fit in the area I use small barrel sanding bands, and also sometimes round diamond burrs to smooth things out. From there, I use a mixture of silicone bits and 3m bristle wheels to further refine the texture and finish.
I have had no luck with cratex wheels or anything like that for sprue removal. I’ve also never found cutters that can cut a chunky sprue particularly close- I’m still left with a very big lump to remove. If anyone has cutter recommendations, I’d love to know!
Gold or silver? With silver your time is worth more than metal recovery. With gold for me it is the other way around.
If I tree up with plenty of space I can cut the sprue from the tree then cut the feed sprue from the piece. End cutters I have found I can get the closest without harming the piece. The best I have found is the Bergeron compound end cutter. Goes through fresh cast silver and 14kt like butter. White gold it can chip the blades.
With gold I am trying to save all the metal I can and find a file and country music work best. With silver I use a white silicone wheel on the flexshaft, breathing filter is a must, and Lynard Skynard music. Time is money and I don’t care about the silver recover plus the silicone makes a mess but no heat.
I’ve experimented with all kinds of cutters. Bold cutters meant for steel cut through 12-15mm sprues for recasting with ease. I’ve got doctor pin cutters for stainless and titanium that cut through feed sprues. Metal wire cutters, nail cutters, The Bergeron work best for me with older arthritic hands.
When I’ve bought clip and ship castings from a professional casting house I am amazed at how close they cut the sprue. It only takes a couple of swipes with a file. I’m sure those are hydraulic cutters with special tips that are sharpened on a regular basis. If you are on the mid-Atlantic area and want to try a few different cutters, give me a private message.
Hi all, I would add the Kate Wolf belt sander on the flexshaft and sand the sprue after cutting. There is an excellent tutorial on Youtube, the tool is very handy and surely quicken the job!
Thank you all for your suggestions! I’m cutting through brass, and just
bought some cutters and a few wheels to try out. It’s good to hear that
there’s a certain amount of filing and sanding by hand that has to happen
regardless — good to know I wasn’t missing something super obvious!
Thanks again for your recommendations, I’ll be hanging on to this thread
Depending on the quantity of pieces you need to work with and the fact your are using brass, an inexpensive bench grinder may be a good tool to use to take the bulk of the sprue before you need to use sanding sticks/files, etc. for the fine removal.