How To Determine Correct Motor/Controller

[Will-CRParticipant @will-cr]

Hi all,

 

when it comes to the electronics side of things I’m afraid my knowledge is very much lacking. I have a Champion no1/G.H Thomas hybrid (will attach some images) that I’ve restored and am very much looking forward to using (return spring yet to be installed) however I’m stuck when it comes to the motor/controller side of things.

I’m looking to:

A)get some advice on what spec motor/controller will be suitable to run this machine.

B) there’s no doubt I’ll have to get/replace a motor on many a thing in future so is there a rule of thumb or way of calculating the right kind of motor? Because at the moment I haven’t the foggiest on the issue and I feel it’s a part of machine work that’s often overlooked.

Thanks,

Will

[Clive Brown 1Participant @clivebrown1]

My version is pretty much 100% GHT, I use a 1/8hp, 2800rpm, 240v. mains induction motor which I find plenty in conjuction with the 5/32″ capacity chuck. A niggling feature is that the 5mm plastic bel has a fairly lengthy run and tends to stretch when loaded even with quite small drills, with consequent whipping about.

Have to admit not using this drill much, since my Fobco is good with small drills. It’s normal use is as a tapping aid.

[noel shelleyParticipant @noelshelley55608]

For something like a small drilling machine I would say a quarter or 1/3 Hp( about 250watts) motor and running at 1425rpm. This is a simple single phase motor that should be easy to find UNLESS you want to go down the road of variable speed ? Then it’s up to you how much you want to spend or how complicated you want it to be. There’s brushed and brushless or 3 phase. Good luck. Noel.

[duncan webster 1Participant @duncanwebster1]

5/32 drill wants to be doing about 2400 rpm, so 1425 is a bit slow. I’d go with similar to Clive

[bernard towersParticipant @bernardtowers37738]

I notice your belt is an orange one, I tried them and found them too flexible and now use the green ones on both the UPT and the cutter grinder.

[JasonBModerator @jasonb]

With the small choice of pullies I would have thought something a bit more upto date like a sewing machine motor with variable speed would be a better option and possibly what the OP wanted as he asked about a controller.

Even if you did go with a 1450rpm motor as Noel suggests, your 3 spindle pullies would allow you to go up or down from that if you had the motor pully the same dia as the middle of your three so likely to get 700, 1450 and 2100. rpm. Changing that to variable speed could see anything from 350 to 4000 if the bearing arrangement suits.

[IanTParticipant @iant]

Yes, I got feed up with the foot mounted motor on my small drill and bored out an old cast-iron bracket to mount a 200W DC motor directly on the back, with an in-line belt drive. The ply motor mount ended up an L-shape so the belt tension could be adjusted via slots in the side extension. The motor came with an IR controller & display to vary the speed and I decided to keep it ‘as was’ and just 3D print a case. I don’t need to move the belt in practice now.

Not the best picture I’m afraid but hopefully you will get the general idea. This arrangement works well for drilling in the 1mm to 6mm range which covers much of what I do in modelling terms. I have other drills to handle anything smaller (<1mm) or larger (upto 14mm). I also have various small vices & tapping accessories that fit it too. The white wooden work table shown is being gripped in the jaws of a small X-Y table with the usual drilling table swung out of the way. I have other ply ‘sacrificial’ tables (e.g ones I don’t mind drilling holes in) that I can glue/screw flat work to if needed. Not quite to GHT standards but it all works well enough for me…

IanT

[noel shelleyParticipant @noelshelley55608]

Considering the plain bearings running the unit at 2800 or even faster would soon see a failure. Ian Ts adaptation is neat and gets rid of the 2 small idler pulleys but you are still left with the main spindle bearings – plain or ball ?  This dinky little machine was designed in a different age and a simpler world. Noel.

[IanTParticipant @iant]

I think they are probably plain bearings Noel (there are two oiling holes in the spindle) but it’s been a very long time since i last dis-assembled it. There is a ball-thrust bearing on the spindle nose though which I feel is a good feature to have on a low power drill. I give it a squirt or two before use and I’m pretty sure she will see me out.  🙂

Regards,

IanT

PS That ‘old casting’ was part of a German made ‘paper-drill’ tossed in the skip when my then employer moved office. It was quickly transferred to the security of my car’s boot and yielded a very nice AC motor which is still giving excellent service on another machine. The casting seemed too good to throw out, so it sat on a shelf for over 30 years before finally getting bored to size and reused. However, the time has come where many of my ‘Too good to Throw’ treasures are going to have to take a final ‘Trip to the Tip’  🙁

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