So I finally convinced my contractee to ditch the 100% hand assembly for PTH circuit boards, and invest in equipment for manual dip soldering. We'll still be hand populating, but hoping to streamline the rest of the assembly process.

To that end we're trying to figure out a lead cutting machine as well. Here's a video for those not familiar:

Mostly I need help finding a large diameter flush cut blade, ie. a blade without an arbor, or where the cutting surface extends beyond the end of the arbor (otherwise the arbor would interfere with any leads that would cross it's path.)
So far the only things I'm finding are type-27 (recessed hub) cutoff wheels for angle grinders. But most all of the pics/videos of lead cutters I've seen look like they use flat blades, where the blade is simply attached to the spindle all as one piece?
Any ideas where/what I should be looking for? Looking for something 4.5" or larger diameter.

Beyond that, there's the issue of frame assembly for the cutting machine. The initial plan is to use some aluminum channel as tracks for the PCB and mount those in a t-slot frame so that the height of the PCB can be easily (relatively I hope?) adjusted per the desired lead length of a given board. I have some reservations about how sturdy such an assembly might be ...leaning more toward a welded frame assembly, at least eventually (but I imagine the requisite precision needed for uniform lead length will come at a cost for something welded & adjustable).
Just wondering if anyone has ever given any thought to designing or building such a machine?

 

I think there has to be more going on there than you think. There may be one rotating blade but here would need to be a corresponding back up blade that that acts as the shear point. But to answer your original question, think you're looking for what is called a "circular razor cutting blade".

Just one of many places that sell them - https://www.carolinaknife.com/resources/razor_slitter.php

 

I said this on the other post but that spinning blade gives me the shivers. I wonder how many fingers have been lost on that machine?

 

After having just implemented a DIP soldering machine the worst part about it is controlling the fumes..
I ended up having to put a 1000CFM blower on it and directing the "fumes" straight outside..
Without that it quickly stank up a 5000+sq foot assembly plant..
Same for the fluxer.. Without sufficient shielding/ventilation you will be taking your breath away.
I would recommend an enclosed selective fluxer for that..

Now these DIP machines are used all the time in 3rd world countries where worker health/safety is at the back of the line so my comments are about trying to implement these in the US or similar areas where OSHA/workplace safety,etc... is a big issue..

To your question though..
Just source the same blade used by those machines and make your own machine if you want. They always sell replacement blades at a reasonable cost.. You will spend more time/money trying to reinvent the wheel vs just buying the wheel
I agree there "could" be some cost savings in driving that wheel but calculate the time in design/material procurement/building the machine,etc.. and most times its cheaper to buy the whole machine too..

You will easily save money going DIP vs manual hand soldering.. enough to easily justify purchasing all the required auxiliary equipment too..

I know.. I know.. You "can" build it though (I suffer from the same.. want to do it myself mentality) .. I'd bet you will find you can't do it for cheaper though when you factor in everything.. Stuff like this is rarely cheaper to make a one off..
Some stuff. sure.. a lead cutter though.. doubt it..

 

After having just implemented a DIP soldering machine the worst part about it is controlling the fumes..
I ended up having to put a 1000CFM blower on it and directing the "fumes" straight outside..
Without that it quickly stank up a 5000+sq foot assembly plant..
Same for the fluxer.. Without sufficient shielding/ventilation you will be taking your breath away.
I would recommend an enclosed selective fluxer for that..

Understood. We've already got a fume hood, installing duct work to vent outside this week.

To your question though..
Just source the same blade used by those machines and make your own machine if you want. They always sell replacement blades at a reasonable cost.. You will spend more time/money trying to reinvent the wheel vs just buying the wheel
I agree there "could" be some cost savings in driving that wheel but calculate the time in design/material procurement/building the machine,etc.. and most times its cheaper to buy the whole machine too..

You might be right, but we already have an unused router and table/frame, plus any excuse to put the bridgeport mill to work =P I haven't had any luck finding the actual blades so far. I guess I just need to email the manufacturers.

You will easily save money going DIP vs manual hand soldering.. enough to easily justify purchasing all the required auxiliary equipment too..

Any thoughts on buying a manual lead forming & cutting machine? I've wondered if it might speed things up for populating the boards. As it is we use bulk passives which we manually form as we place them. I know the cutting machine would be great if we were still going to hand solder (since no more forest of tall leads to navigate on the solder side) but not sure if it will make much of a difference for dip soldering.

 

I think there has to be more going on there than you think. There may be one rotating blade but here would need to be a corresponding back up blade that that acts as the shear point. But to answer your original question, think you're looking for what is called a "circular razor cutting blade".

Just one of many places that sell them - https://www.carolinaknife.com/resources/razor_slitter.php

Are you referring to the lead cutting tools used to trim leads before populating? Because my question was about cutting the leads after soldering, and I'm pretty sure the machines I've seen use a single abrasive blade for that.

 

Any thoughts on buying a manual lead forming & cutting machine? I've wondered if it might speed things up for populating the boards. As it is we use bulk passives which we manually form as we place them. I know the cutting machine would be great if we were still going to hand solder (since no more forest of tall leads to navigate on the solder side) but not sure if it will make much of a difference for dip soldering.

Absolutely going to be faster.. We have a manual (hand crank) cut/90 form and another automatic cut/and locking lead former to create the standoff kink to keep high power resistors a set distance off the board..
90% of what we do is axial resistors or diodes..
We also have DIP lead "straighteners" which work great for DIP packages that come in tube form to straighten the leads on 4+ lead devices to make them quicker/easier to insert in their holes..

ROI depends on quantities.. there are used machines available all the time though on ebay and the industrial auction sites..

If my volume was enough I would have an odd form pick/place machine that would cut/form/stuff the TH components right into the board and eliminate the human stuffer for as much as possible..
It takes more to populate/stuff the boards than anything else..