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72 Posts
Discussion Starter · #1 ·
So a while ago I bought one of those tiny bench drills, really cheap and underpowered. I rigged up a 3 phase motor to it and that gave it plenty of power. It was still too small and too flexible. Any sort of decent force on the drill would bend the head away from the table.

So I took the quill out of it, which suprisingly had a 16mm spindle and set about making a new frame for it all.

Some 100mm x 10mm plate was tacked onto a length of 80x80x6 box section, spending a lot of time getting them square and centred.

Then it was all precariously balanced under the pillar drill ready to start the long job of drilling and tapping 18 holes.

All 18 drilled countersunk and tapped. And was I hell paying nearly £20 for a 20mm countersink. I used a 22.5mm drill bit.

Time to start the table slide. Two 100x120x10mm steel plates welded together.
First time I've worked metal this thick so it turned out a bit messy, but aslong as its solid then I dont mind.

Had to weld from the back too, didn't penetrate quite all the way.

I didn't know it yet but id warped these welding them together.

Some 10x10 was welded down the sides of the pates. Very scruffy looking ill add

And then some 20x10 on top of that to form a lip on the inside edges

I set that aside to cool and welded some 50x50x5 inside a length of 60x100x6 to create a separation and also double skin the bottom.

Then I bored a hole all the way through it all to insert the quill.

And this is where problems started. The hole had too much slop, even cutting a slot in the front and bolting it up tight wouldn't work.

So annoyed at that i tried the slider, that wouldn't slide as it had warped.

More annoyed by then....

So with out consideration, what if it doesn't work I cant go back or any other useful thoughts. I lopped the front off the old pillar drill and welded it to the steel section.

It worked beautiful, it was nice and square, the welds looked good. Then it cooled down. And the cast iron cracked, in a few places as well along the weld seam. GREAT!

So a 60x80x10mm steel plate had a precision hole bored in it on the DIY lathe, which took about 2hours and an old broken drill bit.

I also cut two 20mm strips of 10mm plate and welded them to the front with 3 high tensile bolts and some weld nuts. That gave me enough force to pull the top of the box in half a mm or so so it would guide the quill without clamping it.

One end sorted, now the other

After cracking the original head I was skeptical about taking measurements off it. So when I needed to attach the the quill handle I drilled the correct sized holes in two 2mm steel plates and oversized through the box section. This gave me some wiggle room to align everything before final welding.

more scruffy welding where this box section joins the spine, the first few passes where neat, I think I tried to stretch the pool a bit wide, never mind I've been over it about ten times the welds very thick now.

Table got sorted. I cut the slider in half and then joined it with a 200mm long price of 10mm plate. This time a clamped it down tight and managed not to warp it.

The plate also has 3 10mm bolts in it to tighten against the back and stop it sliding, lock it on place

Other than that, I've painstakingly tacked the top cast iron bearing mounts on, and managed not to crack it and welded a 300x300mm 10mm plate to the base to stand it up on.

I've also raided my old little compressor for a soft start 2hp motor.

Pulleys and belts are in the post, along with more bearings. Will update as I can.

72 Posts
Discussion Starter · #3 ·
Belts and bearings came, still waiting on pulleys. Thought id update with a pic of the drill stop right way up. Its 1500mm tall, and has a throat of around 330mm.
The table measures 550x500 and is adjustable from a chuck height of 0 (meaning the table will butt up against the chuck) to about 1200mm. Not that ill ever need to drill anything 1200mm tall but there we have it.


72 Posts
Discussion Starter · #5 ·
Thanks, didn't know there was such a section, maybe the next contraption - I despise hack sawing.

I've got a nifty idea for squaring up the table, and it would be even better if the pulleys would hurry up and come...
I've got to modify all three of them to get the right ratios i want.
Two aint available in the shaft size I need so have ordered drillbits to make them the right size, all three are 2,3,4,5" step pulleys. I need ratios of at least 1:4 so I need to machine the 2" steps down to 1", or a little bit over for the 1:4 ratio, bore them out, fit them and make independent belt tension-er, or machine the 3 and 4" steps to maintain a consistent ratio

Once all thats done, and I get the ratios down to 1:4 I should be able to get 12 different speeds from 115rpm all the way to 45,600rpm - which is complete lunacy as the bearings are only rated to 22,000 rpm with a minimal load.
But I have to keep the pulleys opposite and equal so in stepping the speed down, its also possible to step them up.

infact 45,000 rpm is so rediculous I might rethink the belt system, just a little.....
Then again the bearings are £1 each so it could be fun

72 Posts
Discussion Starter · #6 ·
just a quick think, if I left the pulleys standard, 2,3,4,5, there will be 3 shafts, equal and opposite, like any other bench drill.

My input is 2850, x 2.5 (pulley ratio biggest to smallest) and the centre shaft will be doing 7125rpm. Select the same on centre shaft ( big to little x2.5 ) gives a final spindle speed of 17812rpm

going opposite way however

input is 2850, x 0.4 (pulley ratio smallest driving biggest) and the centre shaft will be doing 1140rpm, select same on centre shaft, smallest driving biggest and I get a spindle speed of 456 rpm Which is about 5 times as fast id like...

I have already ordered pulleys, belts, etc but its only just dawned on me that i have very slow, very fast and a couple in between......

72 Posts
Discussion Starter · #7 ·
ok, had to do myself a diagram to work this out, with the aid of online pulley calculators.

If i machine down the 2" step to a 1" step to get my speed reductions, this is what speeds I end up with, and its no longer 12 speed as some are duplicated. fuck fuck fuck FUCK


72 Posts
Discussion Starter · #9 ·
think ive sussed it.
Just panicking over my spindle speeds.

Ill try an explain as best I can. I need to modify the pulleys so I can actually fit them.
But I need to modify them further (turn them to different diameters), so I can get different speeds on the spindle ( drill chuck)

lets say I want a big hole in steel, the drill needs to go very slow or it will burn out the bits all the time and possibly harden or anneal the steel, if it gets too hot.

To avoid having build tensioners I wanted equal and opposite pulleys. All the same size just stacked the opposite direction, biggest on bottom one side, biggest on top the other. If they are equal eg

1" > 4"
2" > 3"
3" > 2"
4" > 1"

Then belt tension is constant and I dont need tensioners.

the problems start when adding a middle shaft.

1" > 4" > 1"
2" > 3" > 2"
3" > 2" > 3"
4" > 1" > 4"

belt tension is still constant as the pulley diameters are equal and opposite, but you start repeating ratios.

i.e moving the belts and getting the same spindle speed.

Look at my first calculation chart up there ^^ black green gives a speed of 759rpm, but so does blue red!
Why have 12 speeds if they don't change speeds?

Also look at red black, 71,000 RPM??? I don't need that! It would burn / snap the belts, or if the belts managed to hit 71,000rpm I would be picking bits of bearings out of my face for weeks to come, thats if the chuck and pulleys stayed attached and didn't kill me

So I am going to have to machine a couple of the pulleys to different sizes, and use idlers to take up slack in the belt.

looking at my new chart below the pulley attached the motor will be 1,2,3 & 4" steps, and spins at 2850 ( the motor speed ) This is not changeable ( yet but more on that at a later date).
The centre pulley has different speeds depending on what pulleys you select with the first belt - this is the numbers in the middle of the coloured lines. The chuck spindle has 12 speeds, by selecting a combination of the pulleys.

Take the top left for example, 2850 black line 570 green line 759.

black line says to put first belt on the top pulleys, 1" and 5". This reduces spindle speed to 570. Green line says to select 2nd from top pulleys 4" and 3" which then speeds your 570 up to 759rpm.

Next one down, keeping belt one in place I have two other places to put belt two. Blue or Red, 3rd + 4th steps giving 427 or 114 rpm. There are 12 different ways to connect the belts so the rpms have been calculated for those aswell.

Notice there is no two colours the same, i haven't gone black black, or red red because I cant have two belts on the same step of the pulley

Hope that explains it a bit. If not my select-able speeds will be approximately as below

114 rpm
285 rpm
427 rpm
570 rpm
759 rpm
1067 rpm
3562 rpm
3800 rpm
7125 rpm
8550 rpm
15200 rpm
28500 rpm

I will also be adding ( admitted I dont know when ) an electronic controller to infinitely adjust the motor speed from 0 to 100%. Although they don't really work that well much under half speed, they have no torque - it may be useful for higher speeds such as 3500rpm I could tweak down to about 2000 and still have enough torque to run a drill bit through something.....

72 Posts
Discussion Starter · #11 ·
Pulleys came today, YEY!! Ordered the wrong sized belts though :oops:

Nevermind. Anyways, lets try and get these to fit, first off I need a 22mm bore through one of them.

That one was easy!

Now a more difficult one

I need this pulley to sit on a solid shaft that doesnt turn, so it needs to take bearings.

An old router bit ground down make a shifty boring tool

took about half an hour a side, as I have no measuring on the slides, I have to take a little cut, measure, take a little cut measure but got there in the end. There is a bearing in each end of the pulley

To get it on the drill, I put 3 nuts on a M8 bolt, welded the nuts together to make one long one and then welded it to the drill.
Put a bolt through the bearings and screw it to the drill and it on

I cant bore all the through the third pulley with a router bit as its too short, also I cant machine the pulleys down as originally planned as they are hollowed out underneath.

I rummaged about and found a cast iron step pulley that is smaller diameters than the ones I bought so ill use that on the motor, but first Ive got the the counter weight off the motor shaft

Got some bearing pullers on it, and drew one end of the case off

Middle core is pressed on and I cant get that off so bugger it, ill take a grinder to it

Rebuilt that and started making a rear mount for the motor

MY grinder died :doh:

Cant do much else without one, so more updates next week when I get a new one

72 Posts
Discussion Starter · #13 ·
You mean you aren't going build a grinder out of an old weedeater and some paperclips??

Tried to rep ya but I need to reload. Awesome work bud.
Thanks, I'd just buy but building is more fun, plus a floor standing drill this big is close to £1000 for one as rigid as this.

They have a lot bigger spindles though, but I dont have the ££ for one.

If i can scrape up enough parts, eventually I am going to fit a massive leadscrew to the table so it has a handle to make it go up and down easily. Once the table moves that easily, I can fit a solid spindle drive instead of the quill, it would be a lot easier and cheaper to get a thicker spindle in it then.

No lol, I did try to make one decent grinder out of two broken ones but they are totally different models and I couldn't get it to fit together.

One has a stripped bevel gear and one has a knackered switch. The 9" grinder is still going but I only have one disc left for it and its down to about 5" already.

Excuses for new toys i think!

72 Posts
Discussion Starter · #15 ·
It would be but they are only about 12" long (300mm). I need one 600mm at least, 1200mm if id like to keep the whole range of movement I currently have.

Also because of the weight of the table, and eventually I want to add a milling table I think I will need one a lot thicker than a jack, to stop it flexing.

Kudos for thinking of it though

72 Posts
Discussion Starter · #17 ·
Well, thought I had this all wrapped up yesterday, tensioner system built, electrics wired ( or most of them), table on etc.

Went to use it today and the bloody thing runs backwards.

Motor cant be reversed as the wires are connected straight to the windings, no terminal posts or anything.

So I had to spend a few hours today sorting it out.

The motor had to go 2 feet higher and upside down. The electric box is so large because aswell the NVR switch, ac motor controller and a that little blue switch, there is also a 12v DC transformer stuffed in it and I had to leave room for the digital speed display ( when it eventually arrives).

Capacitor is taped in place for now, it will get a proper bracket soon, also the wires will be tie-wrapped or clipped instead of taped too.

With the motor being flipped over, the pulley was the wrong way, and I couldnt fit it on the shaft the other way, because they are partly hollowed out.

I turned a chunk off ally to fit instead.

Also you can see the crazy belt tensioner system - a stack of bearings keeps it away from the frame

and the middle tensioner - just push it onto the belt and tighten the allen cap bolt.

And heres how I made the tensioner rollers or idlers what ever you wanna call 'em

Tube bored out at both ends in lathe to accept bearings

Bearings will sits on some threaded bar like this

and the tube goes over the top. The threaded bar is just threaded into a bar of ally, with the other end bolted to the drill.

Also as I need a 12v feed for the digital speed display, I fitted some leds behind the chuck, helps to see your marks when your hunched over it casting shadows

Its all working now, and going the right direction, until the digital speed display shows up, ill use it as is.
Once that's fitted, ill give it a quick tidy up and coat of paint
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