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  • Knobs

    Some time back I had a customer ask me for some large head shoulder bolts for clamping screws for his molds. I didn't really want to make them, but when I shopped around I couldn't find anything that fit the bill. I did find a plastic head one, but since plastisol is kicked at 350F degrees and is sometimes injected hotter. Also sometimes guys preheat molds on a hot plate. I wasn't really crazy about that idea, and I wanted something that could be used for lead casting molds too if I was going to make and stock it.

    I found the easiest way to make them was to make an aluminum knob with a knurled head and a shoulder below, then drill, counter bore and tap the knob. This made it easy for me to run in a stainless socket head screw of whatever length was suitable for the particular mold. Its somewhat time consuming to make a batch of them, but I setup a small tailstock turret on one of my smaller lathes for drilling, counter boring and tapping the two most common sizes I use in molds. The tools all stay in the turret all the time. I rough, knurl, and part the knobs on one machine then shove the shoulder in a collet on another to drill, counterbore and tap. Its not fast, but its the most efficeint method I could figure out without going to a CNC lathe with gang toolng or turret type tool post (or both). t takes me several minutes per unit at best. I figure a good CNC setup or screw machine could crank them out in half a minute per part or faster.

    Back to the original project. I gave the customer a price and a bulk price that would cover my time. I figured he would baulk at the price and that would be the end of it. Nope. He bought 25 of them.

    As time has passed I've sold a few off of my website. They are expensive, but the feedback I have received has been overwhelmingly positive in regards to safety and productivity of having a toolless clamping screw they can grip with a glove on. Well for those who have bought them. I have received some negative comments on social media. Mostly about price.

    I also make a few other products not directly related to mold making. I'm in the process of developing a couple right now. Nothing new or original. Just product improvements on old ideas. One I wanted to update a little and use knobs / shoulder bolts. Make it a little faster without having to hunt for a wrench or a hex key. I didn't really want to make more knobs and shoulder bolt knobs, so I started shopping for something that would fit my design or that I could modify my design to make use of. There are some potential knobs and shoulder bolts out there but they are kind of expensive. My price is actually in line with small quantity vendors, and none were exactly what I wanted.

    Now I could probably contact a screw machine shop or post an RFQ on one of the machining sites and get a decent per unit price on exactly what I want if I purchased 10K units at a time. Since the product will take three different clamping screws and I figure I'd probably only sell a couple dozen a year at best. More likely a handful. That's just to much outlay upfront. I might not live long enough to take advantage of the savings. So... for small quantities its cheaper to (figuratively speaking) buy them from myself. If I "pay myself" to make them at the same rate I charge a customer to make them for them I make a few sheckles off the knob as part of the other product.

    Now for those negative nellies who always read a post like this for the purpose of finding something to be crummy about... bug off. I'm neither bragging nor asking for help. I posted this as a maybe bit of help or push for people who are always looking for something to make and sell. Its not worth it for you to make one (1) knob for anybody, but if you find somebody who needs small quantities and you can make 10-20 at a time you can pay yourself a fair wage for standing in front of your lathe. If they suddenly want a bunch you can always post an RFQ for a screw machine or CNC lathe shop. I don't mean to say you should go out and make knobs or shoulder bolts persay, but there are low to medium demand products that you can make and sell that will atleast pay for the material for your own projects. Stuff that retails high enough after distribution that it costs more than you think it should. You could price match retail, and make a product that more exactly meets somebody's needs. Many of these things (like aluminum or even steel knobs / shoulder bolts) don't require any more tolerance than you can easily produce on a cheap import machine.
    Last edited by Bob La Londe; 02-27-2020, 12:14 PM.
    *** I always wanted a welding stinger that looked like the north end of a south bound chicken. Often my welds look like somebody pointed the wrong end of a chicken at the joint and squeezed until something came out. Might as well look the part.

  • #2
    Yeah, it's a niche, and I can't even count the times I've wanted something made out of aluminum or whatever. But at the same time there's no way I could justify "big boy" equipment. The monthly payments on a new Haas are going to start at something like $750 and you need a good compressor, a bar feeder, tooling, etc etc... at my day job, they are using war production machines that came with the building which was abandoned. Because the spindles still turn and thats good enough for them.

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    • #3
      It seems like this is where the "old way" with a turret lathe could come in handy. A machine that holds a number of tools with travel stops that allows reasonably rapid small numbers production runs. Yet isn't a bad lathe to have as a "second operation" machine if one has the room and is using their home shop to make a few extra dollars.
      Chilliwack BC, Canada

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      • #4
        You mention "my website" but there is no link. Maybe there's a rule here about self advertising? Only asking because I'm curious to see these things (and others) you may be making.
        "A machinist's (WHAP!) best friend (WHAP! WHAP!) is his hammer. (WHAP!)" - Fred Tanner, foreman, Lunenburg Foundry and Engineering machine shop, circa 1979

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        • #5
          I think a problem with CNC is everyone thinks big numbers.
          When I had my turret lathe, I could run 50 or 100 quantity no problem.
          Since then I did a few other knobs in brass, on my regular lathe using my 4 way toolpost. 4 way can be fairly effecient, and if you are drilling the piece, it can be one shot with a good stub drill, and second op if you need counterbore or tapping.

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          • #6
            Originally posted by BCRider View Post
            It seems like this is where the "old way" with a turret lathe could come in handy. A machine that holds a number of tools with travel stops that allows reasonably rapid small numbers production runs. Yet isn't a bad lathe to have as a "second operation" machine if one has the room and is using their home shop to make a few extra dollars.
            My dad tells stories of a neighbor who had a Brown and Sharpe automatic screw machine in his basement and made a good buck on the side with it, supplying small parts to GM during and after the War. Those were the machines where you had to mill a set of cams to define the turret movements.

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            • #7
              Before they were bought up, Reid Supply made many cast Iron knobs and handles that were just like the ones you might find on a 25, 50 or 100 old machine. Now their catalog is a lot more sparse and contains mostly stuff from other suppliers.

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              • #8
                Jergens still makes knobs I think, and KBC has some..

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                • #9
                  Originally posted by nickel-city-fab View Post

                  My dad tells stories of a neighbor who had a Brown and Sharpe automatic screw machine in his basement and made a good buck on the side with it, supplying small parts to GM during and after the War. Those were the machines where you had to mill a set of cams to define the turret movements.
                  I've read about machines with the tracer or cam feature. It may or many not have been a common feature on all the turret lathes. Mostly it's the big 6 or 8 position "tail stock" which could do so much for something like making knobs like this. And the multi position tool post for holding a few turning tools and a parting tool. All of then using stops to control the work.
                  Chilliwack BC, Canada

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                  • #10
                    Originally posted by mickeyf View Post
                    You mention "my website" but there is no link. Maybe there's a rule here about self advertising? Only asking because I'm curious to see these things (and others) you may be making.
                    Yeah, if I want to advertise here I have to buy an ad. I don't want to try and sell to you guys anyway. My posts are either argumentative or sharing usually. This was intended to be a sharing post.
                    *** I always wanted a welding stinger that looked like the north end of a south bound chicken. Often my welds look like somebody pointed the wrong end of a chicken at the joint and squeezed until something came out. Might as well look the part.

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                    • #11
                      If you are looking for stock, aluminum knobs, the electronic market has them in almost any style you can think of. Most from electronic supply sources will have a 1/4" shaft but a solid aluminum knob can be bored out for a larger shaft.

                      Cut the head off a standard shoulder bolt and put the knob on it. For this application I would suggest a spring pin for attachment as set screws can work loose.

                      Electronic suppliers:

                      DigiKey
                      Newark
                      Mouser

                      Some brand names for aluminum/metal knobs:

                      APEM inc.
                      Keystone
                      Kilo
                      TE Connectivity/Alco Switch
                      Ohmite
                      Paul A.
                      SE Texas

                      Make it fit.
                      You can't win and there IS a penalty for trying!

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                      • #12
                        Bob, I prefer "discussional" over "argumentative"....

                        Seriously though, if you do repetitive items to help your shop earn its keep would an old good condition turret/screw cutting lathe be a decent fit for your work? Just curious on this sort of idea.

                        We don't see much 'round this forum on turret lathes. Yet there are so many of them out there. I sometimes would not mind one over a more general purpose "engine lathe" in a way. I think the turret could be adapted to do pretty much everything that the tail stock does. The downside is that turret lathes tend to be short bed lengths for center to center spacing for a given weight category.
                        Chilliwack BC, Canada

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                        • #13
                          I wouldn't mind seeing a picture of the clamp and set up - it'd be interesting to see this particular solution. Never know but sometimes things like that can be adapted to other situations.

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                          • #14
                            you want knobs? jwwinco They got knobs.

                            I've made a few special ones of the years for fixtures, and it's almost always cheaper to buy them and modify them, or use as is. On the other hand, the times when I've had to make something special was for quick turn around stuff, and there was no time to order something. Not even from mcmaster.

                            We've got an in house product that we use about 200 a year of that I designed that uses special knobs from JWWINCO that I linked above. I tried making my own from solid bar but came in about double what they charge. That's in a bar fed CNC lathe. I knew I'd be more expensive but didn't think I'd be that bad. That's even before blackening them too. Now the jwwinco ones aren't perfect for how I want them, but for the price they'll have to do.

                            Have you thought about machining a steel mold and casting aluminum around the head of a cap screw? I've always wanted to try that. Few year back I made a mold for casting lead dead blow faces like that and that's when I got the idea for casting aluminum hand knobs too.

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                            • #15
                              Originally posted by mattthemuppet View Post
                              I wouldn't mind seeing a picture of the clamp and set up - it'd be interesting to see this particular solution. Never know but sometimes things like that can be adapted to other situations.
                              Not a clamp. Clamping screws (in the case of molds). Imagine a two part mold with one side drilled and the other side drilled and tapped so you can use simple machine screws to clamp the halves together. An ordinary machine screw requires a wrench of some kind, but a large knurled knob can be tightened nearly as firmly by hand as an ordinary machine screw with something like a short arm hex key. No tool is required to snug down or release the screws, and they can be easily managed when wearing heat protective gloves while injecting or casting. Ever try to pick up a hex key or a smallish machine screw off the bench while wearing gloves?

                              I am looking at similar knobs for another item I am working on. Not so much for gloves, but to make for quick toolless adjustments. I'm also looking at ideas for something similar for hex keys for some applications. Easy to manage, and even easier to pick up than a t-handle. Sometimes you can't use a knob in place of a screw, but your "wrench" can have more than one kind of handle.

                              By making a knob that a machine screw is threaded through if it does get overtight for some reason (snugged down in a cold mold and then poured or injected with hot media) a hex key can still be used to get a little more leverage.
                              Last edited by Bob La Londe; 02-27-2020, 06:33 PM.
                              *** I always wanted a welding stinger that looked like the north end of a south bound chicken. Often my welds look like somebody pointed the wrong end of a chicken at the joint and squeezed until something came out. Might as well look the part.

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