Thanks for a way to avoid buying a broaching set. In fact it gives me a ideal how to make a broach using a boring bar and a arbor press. Seems like the help offered on youtube by true people sharing information and not trying to sell it is a great thing.
Once its location is known (from the first few passes) I take a small file and file a small lead in so the initial cuts are not as 'jarring'. Great video.
My Bridgeport motor died so I bought a replacement, but it's got a .875" shaft versus .750". Now I can bore it out and cut a key in it on my Southbend Heavy 10 without a 200$ broach set, sweet!! Thank you... PS - To those that have a lathe, you can also but an end mill in your chuck, find a way to mount the shaft on your toolpost, and cutin the keyway 1/16th smaller than the actual size required; then on your final cut, switch to the 3/16ths or whatever end mill you need.
I am doing the same thing here now. I was getting a lot of deflection and a tapered slot. Then I found your video so I know it can be done. I will try again. Thanks for sharing this technique.
If you have vertical mill, can just dive an end mill straight down the keyway on the center radius. The upper curve on the radius doesn't really matter since the flat will stay pushed in anyway. Or just use round-stock as a key, flatten one side on the shaft and round fits perfect into milled key slot.
My understanding from the Clickspring video on this technique is that the weakest point in the power train to the cutter is in the hand wheel, so does that mean you could potentially use the power feed with the spindle disengaged to get a bit more cutting power?
+Rob Mckennie No. The gearing for the leadscrew which powers the power feed is run off of a gear at the end of the spindle. It's not so bad. Just go slow and don't take a huge bite.
***** aren't the spindle and pulley separate parts? You could disengage the bullgear from the pulley without engaging the backgear, so the spindle and leadscrew with turn independently
+Rob Mckennie The gear that drives the gear train is on the end of the spindle shaft itself. If you wanted to use a feed you'd have to have a handwheel at the end of the leadscrew (English lathes have this) or turn one of gearbox input gears by hand with the tumbler reverse in the middle position.
So I suppose if you haven't got a boring tool or a lathe to hold the pulley you can simply use a hacksaw to start the keyway and then widen it with a needle file. This is a problem I am faced with when there are no engineers to help make a 2mm wide keyway through my flywheel.
thanks for posting I am going to try this on some small parts I have for a project. I am going to cut multiple slots to replicate a crude spline. Also isn't a big advantage having the largest boring bar that can fit to reduce flex?
this is the old form to do the keeway but broching is go better the clue is have you the tools or machinery, but it is nice to see the video how you make your work
Can you imagine how easy this would be if you CNCd your lathe?! I've just about finished converting my G0704, now I want to do my lathe too! :). Awesome tip none the less though.
If your lathe has a back gear just engage that without pulling the bull gear pin. If not there are a few different ways. Cloth rag in the spindle gear, ratchet strap around cone pulley. Get creative.
@@Halligan142 hey, thanks for the reply on a 10 year old video :) i will do one of these, i have a Proturn 410 and need to do internal keyways. i thought about screwing a plug into back of spindle which is threaded then bolting a plate to that plug and the machine housing. i like the rag in the gears though, i will do this. Thanks!!
A broach is an expensive tool that sits on the shelf if you need it one time, for only that one size of broach, and only that one bore for the matched die that goes with it.
neat. It's not really clear if you made the boring bar+cutting bit or got it commercially...did you make it? Looks like it's in a square hole too which must add some complexity if you made it. Update: I found this which I guess is what you might have done: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-eUEul9sdpG0.html
you do know that this will ruin the lathe and make any backlash even worse, so its not recommended unless you are willing to have horrible backlash on your machine
You do know that this is the same type of horizontal stress that the normal tool is exposed to in normal use, right? How, exactly, does this use cause "horrible backlash"?
I suppose if you are using a very small, inexpensive hobby machine it may damage it. However, on any machine which a machinist might be using you would not be able to exert sufficient stress by hand to cause any noticeable wear. You have to remember that the lathe's saddle and compound are driven by the same gearing that drives the leadscrew. The tool pressures are pretty incredible. When you are hand broaching on a lathe normally you are using either the saddle handwheel or a simple broaching lever, neither of which offer a great amount of force. I'm not saying its impossible to damage a lathe. I just assume that we are discussing this with the understanding that the broaching is taking place with a reasonable doc (depth of cut).
rokdevil well if he is being reasonable about the doc then yes the wear wouldn't be anything other than what you would have during normal machining, but using the lathe isn't really the best method for cutting a keyway, although other methods may not be feasible in this situation
Do you have any source to support your claim that that can damage a lathe or did you just made that up? Maybe I'm wrong but you seem like the guy who makes something up (often safety related) just to get some attention.
