Jon (May 17, 2023)
While re-sawn materials are generally thought of as wood, there is call to split metal also. All the things wood does such as spreading open or binding blade, metal does perhaps even worse. . . So a guide like this has a place. Envisioning it clamps to the rip fence.
Sincerely,
Toolmaker51
...we'll learn more by wandering than searching...
Make Things (May 15, 2023)
Thanks Make Things! We've added your Steel Nose Bandsaw Sled to our Sleds category,
as well as to your builder page: Make Things's Homemade Tools. Your receipt:
New plans added on 11/22: Click here for 2,593 plans for homemade tools.
More teeth, yes. Rule of thumb is minimum 3 of pitch to material wall or overall thickness. IOW, 6" tubing of 1/4" wall, or 1/4" plate; same minimum pitch. Most metalworking band stock is not nearly so coarse as woodworking blades. However; good woodworking blades are terrific in aluminum up to 6061. 7075? Get a chair. . .
There's call to split bar stock, really more of a contour job, a connecting rod type shape, plentiful usable remnants. Nothing outperforms band saws in preserving material. Plasma or oxy-acetylene could of course; band saws don't raise such a burr or toughen surface by carburization.
Square and rectangular tubing present different consideration. Those are rolled from flat sheet, via radiused corners, ~ perpendicular sides and submerge welded seam.
They're now loaded with internal stresses. Splitting one way, they'll usually spread open, sometimes closing on blade. A shim of blade kerf+ thickness works. Also depends where cut taken; through the middle or nearer one wall.
The most difficult tubing are those thinner walled with broad faces and narrow edges, creating chatter and vibration of unsupported material. Die springs or adjustable parallels on cardboard can fix that, while steering blade to avoid.
**Somewhere I've mentioned band saws are the pinnacle for separating parts from remnant; least amount of waste in chips, cutting near net of desired part, retaining larger drops for other use....
Very true, 1 caveat versus Wire EDM; yet far more precise, broader range of materials, virtually no chip loss (= wire size), no heat imparted, can create mating parts in one operation, ie punch & die.
Great if footprint, cost per hour, electrolyte, spools of wire and programming are no issue.
Last edited by Toolmaker51; May 16, 2023 at 05:50 PM.
Sincerely,
Toolmaker51
...we'll learn more by wandering than searching...
You do want to slow the bandsaw blade down from the wood working speeds when going to metal with bandsaw blades that are intended for steel. 100 surface Feet per minute (SFPM) being the typical high carbon heat treated blade speed (blades can get expensive with bi-metal HSS cobalt). That may be possible with step pulleys, or intermediary jack shaft. Easiest that I've done is put a 3phase motor on the saw, and drive it with a VFD (variable speed drive) and slow it down to the needed SFPM.
This makes switching back to wood easy. VFDs have gotten very affordable. I've had good luck with used ones off eBay or local Craigs list or FB market place. Just make sure it's a 200 class series (intended for 240V operation, vs the 400 series for 440V operation). I've never had and issue with single phase input creating the needed 3PH output. But there are some that have a phase loss detection on the input. So download the PFD manual for the model you're looking at and check that it can run on single phase. Under 3HP you don't need to derate the VFD, the limiting factor is the input rectifier diodes. Over 3HP, they typically derate to using twice the VFD HP of the motor your driving.
VFDs typically have a programmable display, where you can insert a scaling constant to convert hertz to spindle RPM, or in this case SFPM so you can dial the speed in quick with the potentiometer on the front panel of the VFD.
The other rule of operation, NEVER switch the VFD to motor output connection, as that can blow the VFD transistors up. They really are easy to connect to the motor. And there's many ways to start and stop them, with external switches and such. It's all in their user manuals. If you can't find the PFD of the manual, don't buy it. I've typically only seen that on Rockwell Automation, that seems to delete older models from their web site.
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