Hamilton Varimatic Sensitive precision Drill Press
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  1. #1
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    Default Hamilton Varimatic Sensitive precision Drill Press

    Locally, I found an old Hamilton Varimatic drill press whose former owner was Boeing. I should have dickered a bit on the price but wound up buying it for $200. Not a bad deal considering what these cost originally! But it needed a full teardown and restoration. There's a video of that process here:

    Plus I used it to drill a .0135" hole

    YouTube




    So now it looks great, and functions WAY better. But there's still a bit to do. I'm having trouble locating a replacement belt. There is one on Amazon but the lead time of 4-6 weeks does not give me confidence: Sorry! Something went wrong!

    I've also talked with Rebb Industries who still (sorta) support these machines. They're out of stock on a new motor contact disk but are doing a new production run and will charge me around $125 for a new one.

    The big question is if I should (or should not) replace the bronze bushings and/or the spindle shaft. I guess I don't need to based on the accuracy of the drill, but if you watch the video you can see a little tremble in the drill bit when I'm drilling the dime. It's hard to determine if I have any appriciable runout or not. Apparently the factory spec on these is .0002" TIR, and mine SEEMS to have .0003" but it's pretty hard to measure. There is some wear on the spindle itself too, but it's pretty minimal. I can only really tell it's there when the spindle is on a surface plate and there's a light behind it. I don't know what my expectations should be, but I've come so far with the restoration it's tempting to just go all the way.

    Open to ideas.

  2. #2
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    Nice paint job and general cleanup.
    From the video I couldn't determine if the replacement bearings for the spindle were just ordinary bearings or high precision ones. However, by hammering them in place like you did, it wouldn't have mattered much having used high precision ones.
    Personally, I would say that a 0.0003" TIR, if measured on a pin in the chuck, is rather impressive and I would be extremely happy with it.
    The investments in making it slightly more precise, I'm afraid, would be considerable and I'm not sure if you would be able to take advantage of having a TIR of 0.0002", instead of 0.0003" (unless you added an extra zero in your initial post).
    A few of the things involved would be purchasing high precision bearings, time the inner races to compensate for the residual runout of the spindle/chuck assembly, press them in place perfectly square in the frame using a press, by pressing only on the outer race, etc.

    Paolo

  3. #3
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    Maybe you have already tried this but perhaps your local industrial supply housecould supply you a belt from
    Habasit
    USA
    or Gates
    Homepage | Gates Corporation
    or some other belt maker for considerably less money .
    The web sites usually list their local distributors .
    Jim

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    I will look into those belt suppliers, thank you. I did call the "new england belt company" who makes the OEM belt. They'd be happy to make some belts for me, but their minimum order was 22, which meant the cost would be over $600. That's not going to happen.

    As to the bearings, the video shows tapping in the motor bearing, which is not critical. The more important bearings are the spindle bearings which were pressed in. I cant' quite figure it out though because the spindle bearings hold a sleeve with a key that rides in a slot in the spindle to drive it. But spindle is somewhat loose in the sleeve. These bearings are not especially high precision, they're regular ball bearings, not angular contact tapered bearings. There is no provision for preloading the bearings, so I'm pretty sure that these were never contact bearings.

    I think the accuracy of the runout and spindle is defined by bronze (?) bushings which are the most outer part of the holding assembly. But I can't quite figure it out. disassembled, the bushings are a very close tolerance fit to the spindle, basically a slip fit. But in some places the must have a tiny bit of wear, and there's no friction between the spindle and the bushings. Which makes me wonder if creating a new spindle and replacing the bushings would change anything.



    Ultimately maybe it's a thought exercise: does it matter? The drill works well as it is. Maybe at very light load and high RPM the spindle just aligns itself without much runout and I should just not worry about it. It does show .0003" runout on a pin when I test it, but it's a little hard to trust my tenths indicator, and I don't really know if that's over the entire range or what it looks like spinning at speed vs. hand rotation.

  5. #5
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    There is another older thread about a Hamilton drill here and there may be more.
    Old Sensitive Drill, Heavy duty, a Who Made it question????
    If you use the forum search for Habasit there are several threads where they are mentioned that may offer some more information.
    I didn’t check them all out.
    At one time there were Habasit service people that would come to industrial shops and glue the belts in place so that you wouldn’t have to take a lathe spindle apart to change the belt .
    I’m not sure of the cost but you should just be able to order the length you need already glues up .
    I wouldn’t expect it to be al that expensive.
    I have bought some much shorter flat belts of some of my machines from a Gates distributor of the type that your machine appears to have and they were in the $ 10 to $ 20.00 range as I recall some time ago .
    Here is another company that my local supplier sourced flat belts from for me at one time again they may have only been a foot or two long but not that expensive.
    https://megadynegroup.com/en/products/flat-belts
    I had posted this link in another thread .
    you have done a nice job cleaning up your drill.
    Regards,
    Jim

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    If it is a simple small section flat belt as used on my non-vary speed Hamilton McMaster-Carr can provide. They have them made to order/length with about a 2 week lead time. Reasonable pricing ,had a couple made for my Themac TP grinder.

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    Thanks for all the belt information. And the link to that other thread: For anyone who owns one of these drills, that's the best thread on the whole internet for parts supplier information.

  8. #8
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    I have an old flat belt High Speed Hammer drilling machine that was in a horrid state when i found it on Craigslist. Disassembled, cleaned and repainted with blue-green hammertone paint. I replaced the upper bearing assembly for the overarm and made a new belt tensioning rig. I didn't replace the main spindle bearings and am using a leather belt from a thift show that i cut and sewed together. Works great. Really lovely machine. Fortuately i already had a nice old jacobs chuck with the right taper.
    Could take and post a few pics if you'd like.

  9. #9
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    If you shifted the hole down a bit you could have given him an earring.


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