Drill Press as Lathe

Discussion in 'Techniques' started by Bruiser, Feb 7, 2019.

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  1. Feb 7, 2019 #1

    Bruiser

    Bruiser

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    So I need a heavier transition for a model I am building and I thought I could use my drill press to turn it. I started with a piece of basswood and drilled a 1/4" hole thru the center. I inserted a carriage bolt and locked it in place with a nut. Then I chucked it up in my drill press and rounded it out with course sand paper. Then I attempted to size the end that goes into the body tube and when I took it off the drill price to test the size I noticed the shoulder was not uniform around the shoulder. It was around 1/16th on one side and 3/32nds or so on the other. I don't understand happened. That's just not gonna work so I was hoping someone could tell me what probably went wrong.

    Thanks,
    -Bob
     
  2. Feb 7, 2019 #2

    rharshberger

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    Usually its because of two things, first a drill press doesn't have a lot of stiffness on side to side pressure. Second the method of "turning" combined with the side play issue can make the issue worse. Most drill press "lathe" add-ons I have seen have the end opposite the chuck captured in a bearing or something to prevent flexing of the mandrel. I am guessing the 3/32" side was the end opposite the chuck, as it flexes more.
     
    Last edited: Feb 7, 2019
  3. Feb 7, 2019 #3

    Trident

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    You probably should glue a dowel into your block of balsa or basswood, so you get no movement of the wood on your “mandrel”. You are undoubtedly getting wobble. A drill press makes a lousy lathe, but if you do everything to minimize slop, you can get pretty realso nable turnings. I bought a lathe years ago, but as a kid I turned nose cones on a hand drill clamped to my mom’s kitchen step stool, and later used a drill press with some success.

    These intakes and exhaust nozzles (not really visible) on the wings were done on a drill press.

    D9845858-7A90-4085-8677-2B0B69CA9B77.jpeg
     
    Last edited: Feb 7, 2019
  4. Feb 7, 2019 #4

    Bruiser

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    I've done a lot of woodworking but never turned anything on a lathe, even during three years of wood shop in high school. I've cut some more wood and will laminate it tomorrow. It's a complicated piece with the out contours alone, but then it needs to be bored down the middle so an ST-8 tube with fit inside. Then I need to drill three vent holes into the side, 120 degrees from each other. So after it gets all drilled out, I think I need the extra strength of something other than the balsa transition that came with the kit. Plus Open Rocket says I need some weight up front. I just have one caliber showing...

    I don't do cad so hopefully this will make sense. Just trying to show what I am trying to make
    Nike Tomahawk Transition.jpg

    -Bob
     
  5. Feb 7, 2019 #5

    heada

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    Find someone with a lathe or go to your nearest Woodcraft and see if they'll let you use the classroom lathe. The lathe can be used to drill/bore your 120 degree indexed holes as well as the core hole. There are a few here that will turn it for you as well (may have some cost)

    If you need a wee bit more weight and strength, use linden (aka basswood or carving wood) turns better than balsa, has about twice the strength and maybe 1 1/2 the weight. Takes details much better as well.
     
  6. Feb 7, 2019 #6

    lakeroadster

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    The best method is to turn the project between centers. To do that with a drill press you need to buy a bearing that attaches to the vise on the table. Bearings are pretty cheap, you can get them at Tractor Supply. Just chucking a bolt results in excessive run-out.

    And instead of removing the part from the drill press for a test fit, buy a dial caliper. Then you can measure the part in the drill press. Taking the part in and out means you are increasing the chance of run-out.

    If you do take the part in and out, buy a dial indicator, then you can make sure the part is running true before taking off more material.

    Harbor Freight has dial calipers and dial indicators that are relatively inexpensive.

    This guy has some good ideas too: https://nickferry.com/2014/10/turn-your-drill-press-into-a-lathe/

    Good luck with your projects, and kudos to you for scratch building!
     
    Last edited: Feb 7, 2019
  7. Feb 7, 2019 #7

    prfesser

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    If I understand correctly, the hole to be bored is 0.76" and the top of the transition is 0.908" diameter. That leaves a wall of balsa that's just over a sixteenth of an inch thick. I fear that you'll split the balsa in attempting to bore the hole, not to mention how hard it will be to get that hole centered within 0.01" or better. Maybe soaking the upper part of the transition in CA would help, I dunno.

    Heada's suggestion of basswood is a good one.

    If you try it in a drill press, the holes for the chuck key are precisely 120 degrees apart, if you can think of a way to use them to index your drilled holes.

    Okay, I'm all out of suggestions. This is a tough one. Good luck!

    Best -- Terry
     
  8. Feb 7, 2019 #8

    prfesser

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    If I understand correctly, the hole to be bored is 0.76" and the top of the transition is 0.908" diameter. That leaves a wall of balsa that's just over a sixteenth of an inch thick. I fear that you'll split the balsa in attempting to bore the hole, not to mention how hard it will be to get that hole centered within 0.01" or better. Maybe soaking the upper part of the transition in CA would help, I dunno.

    Heada's suggestion of basswood is a good one.

    If you try it in a drill press, the holes for the chuck key are precisely 120 degrees apart, if you can think of a way to use them to index your drilled holes.

    Okay, I'm all out of suggestions. This is a tough one. Good luck!

    Best -- Terry
     
  9. Feb 7, 2019 #9

    prfesser

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    When turning on a drill press you have to be careful NOT to apply uniform pressure; the sandpaper will tend to follow the contour of the balsa. If it's out of round at the start it will stay out of round. Use a file to begin, or hold the sandpaper against a piece of flat metal. Bring it up to the work until it begins hitting the balsa; hold it there to knock off that high spot. Slowly move it inward to knock off more high spots as the balsa is sanded away.

    Best -- Terry
     
  10. Feb 7, 2019 #10

    Bruiser

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    You all have given me some great ideas. This is what I was working with yesterday. I can see now how I could get wobble in there with the tail end unsupported. I had also left it an inch longer than I really needed which probably amplified the run out.
    transition.jpg


    Based upon all of your inputs, I am going to change things up. This time the bolt will go all the way thru the piece I am turning and be captured by two nuts. The tail end will go into a hole drilled into a oak block that is clamped to the table. I will check Tractor supply for a bearing. If I can't find a bearing, I think I will turn the tail of the bolt down to 3/16 to get rid of the threads so they won't cut into the block and make the hole bigger. I'll also go to Harbor Freight and check out the calipers because once this thing is all in position it won't come out easy and I should get better results with keeping it in the same place.
    Set up.jpg

    BTW, a few months back I built a mini lathe. I thought I was going to build a whole series of BT-20 sport scale rockets but after the first one I decided that was too small for my old eyes. Anyway I was quite impressed until I used it the first time. The rotary tool burnt up :) I'll have to take a picture of it.

    Oh, that does bring up a question... Is it better to do this at a low speed or higher speed. My drill press has like four different pulleys that you can put the belt on to adjust the speed.

    Thanks for all the inputs,
    -Bob
     
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  11. Feb 7, 2019 #11

    heada

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    Speed: Start slow until you get it round and rough shape, then increase speed. On my lathe, I start at ~100rpm until its round, then increase to ~500rpm to get rough shape. I do finishing (skew, scraper, etc) at ~1500rpm and sand at max which for my 10in lathe is 3600rpm. At the higher speed, it doesn't really allow you to follow the grain so you keep the shape better.
     
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  12. Feb 8, 2019 #12

    Sooner Boomer

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  13. Feb 8, 2019 #13

    lakeroadster

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    Neat thread Bob... keep us in the loop as things progress..

    Dial Caliper.jpg
     
  14. Feb 10, 2019 #14

    Bruiser

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    I stopped by Harbor Freight and picked up the calipers, step drill bits and a wood rasp set.

    This morning I set up my drill lathe with all the tips everyone has given. I bored a hole in the oak block that the head of the carriage bolt fit
    in and then I lubed it with a few drops of oil. I also attached the vertical board to act as a tool rest. I used the wood rasp, a chisel, and sandpaper to shape the popular. I used the caliper to size it to match the booster body tube and the sustainer body tube.
    Drill Lathe.jpg


    I like the way it came out. I do have a few areas to fill with but overall, very uniform.
    Nike T Transition Side.jpg


    Next was to bore out the center. I used two of the step bits to do that. The smaller one drilled a 3/8" hole and the larger one a 3/4" hole but that was the size all the way thru. It's a cone shaped bit and it would only go in so far so I drilled from both the top and the bottom. I did that with fear that it was all going to go wrong because I was holding the transition with my hand while doing the drilling. I just couldn't figure out a way to clamp it down...

    The 3/4" drill was actually .750 and was not quite large enough for the ST-7 tube to fit in. I measured a 3/4" spade bit and it was slightly larger at .768 inch. TO avoid tear out, I open up the hole (top and bottom) with a sanding drum on my Dremel. That allowed the bit to go in a little before it started to drill. I had to go in from the top and the bottom again and this was even scarier than drilling with the step but. The step bit was pretty smooth but this bit vibrated the wood quite a bit and I was afraid it would be ripped out of my hand and destroyed. But alas, my fears were unfounded. I ended up with a pretty uniform hole bored thru the transition that the ST-7 tube will slide into, albeit a little tight, but it goes in. A little sanding and it will be perfect :) A little detail work and it'll be ready for the rocket.
    Nike T Transition Top.jpg

    Thanks again for all the advise,
    -Bob
     
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  15. Feb 10, 2019 #15

    lakeroadster

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    Schweet! Nice job Bob. Thanks for the update.
     

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