Turret spindle thingy project

[Graziano]

Been in the shed cutting up some 150mm wide channel to make the "turret" for want of a better word to mount the homemade ball bearing spindles on. I'd originally planned to angle the three lengths of channel at 45 degrees to the rotating disc so that the unused spindles angle up and take up less space for the unit. Anyway I'm glad that I took the time out to mock up the turret and see how the pieces assembled before doing any welding as the wheels tend to get in the way of each other a bit, once I angled the channel bits to about 30 degrees the distances increased.

Can anyone see a problem with the current setup?, about all I can see is that the access to the tops of the wheels is a bit obstructed, but I don't plan to use the tops anyway.

Edit: I'm also interested in name suggestions for this thing other than "Spurret" :oo:.

When in use the selected spindle will have it's channel base horizontal as per the rough sketch.
http://www.woodworkforums.com/attachments/f65/206922d1335835843-boring-bronze-casting-actually-size-spindle-layout-1.jpg



Original setup with 45 degree angled channel, the channel to channel angle is less than the expected 90 degrees due to the geometry.
http://www.woodworkforums.com/attachment.php?attachmentid=207474&stc=1&d=1336274451


45 degrees with a 200mm grinder wheel and 200mm buff mop propped in position.
http://www.woodworkforums.com/attachment.php?attachmentid=207472&stc=1&d=1336274451



30 degree angle setup with increased clearances.
http://www.woodworkforums.com/attachment.php?attachmentid=207473&stc=1&d=1336274451

[Anorak Bob]

It's worth mocking things up. :2tsup: I'm keen to see how you resolve the turret locking problem. Would a sprung ball detent be better than a dowel?

BT

[Graziano]

It's worth mocking things up. :2tsup: I'm keen to see how you resolve the turret locking problem. Would a sprung ball detent be better than a dowel?

BT

Hmmm, I don't know if a ball detent is going to lock it positively, I expect it could move if you were leaning into the buff mop or wire wheel and giving it some. I seem to be stuck on the taper pin idea, say 10-15mm diameter and pulled out from below by the same footpedal that lifts the motor to slacken the belts. It could be drilled into the turret disc periphery somewhere.

[morrisman]

I am trying to get my head around this project :q

Takes me a while to see whats going on :B

How are you going to drive the spindles ?

It's a 6 station grinder / polisher I think

Mike

[Bryan]

Mark I think belt swapping is going to be tedious. How about a friction drive? As a spindle dropped into position it could engage a drive wheel on the motor.

[Ueee]

Hi Mark,
Looks good, but when you first mentioned this i imagined something more like a ferris wheel. This way you could have your motor back of the center and belts to all 3 heads, but only the front head's belt would be tight. Make sense? I would also use either a taper pin or an arm that pivots into a notch for locking the rotation.

As for the name, how bout MK1 Multi Spurret? (pun intended) Spurret, yet another word to add to spell check.

Ewan

[Michael G]

Well, there are six ends and you are grinding and buffing with it -
How about a "Hexagruff"

One of the things I would be concerned about is flicking metal particles from grinding into a buffing mop. Are you going to have covers for the mops, or just rely on having the right things adjacent to each other?

Michael

[Graziano]

Morrisman: Gee... from the detailed artist's rendering I really thought the entire concept was self evident....:p. Only a single spindle is belt driven, you'll step on a foot pedal to lift the motor and take the belt tension off also unlocking the turret so the next spindle can swing into position and then you hand fit the belts and let the motor drop again.....simple eh??:no:.


Bryan: friction drive might have to be another modification, I'll try the belts for now. I expect infrequent spindle changes........oops now I've jinxed myself!!. I suppose three bench grinders on a turret mount could have been simpler.

Ueee: I had thought of a setup like that, it does get complicated fast, in that you need two posts with the spindles in between on a rotisserie thing (that's a tech term) which may take up even more space than three basic pedestal units and three motors.

Michael: I don't know how I'll prevent cross contamination, a cover sounds good...either that or hope that turning it on flicks a huge shower of crud everywhere on take off. The beauty of inventing stuff is effectively dealing with all the "bugs" as they rear their ugly heads.

So we have "Mk1 Multi Spurret" and a more descriptive "Hexagruff", sounds good, they have a certain ring to them. Hmmm I wonder if I could come up with a plausible acronym based around "CLOACA" or something.

[Anorak Bob]

Hmmm, I don't know if a ball detent is going to lock it positively, I expect it could move if you were leaning into the buff mop or wire wheel and giving it some. I seem to be stuck on the taper pin idea, say 10-15mm diameter and pulled out from below by the same footpedal that lifts the motor to slacken the belts. It could be drilled into the turret disc periphery somewhere.

I like the idea of the pedal operated pin. Rather than root around with a ball and spring which then requires a separate locking mechanism, the pin would locate and lock in one action. Nice.

[Graziano]

The Spurret Mk1/Hexagruff is coming along a lot faster than I expected, been having a few wins and a few issues to overcome. The design issues could have easily been sorted out by making a detailed drawing instead of diving in headfirst. The advantages are as expected, the spindles give room at the rear of the unit so it should tuck into a corner pretty well, you can see from the middle pic that the spindles shouldn't poke much past the motor when wheels are fitted. The use of a mongrel trailer hub and stub axle (Holden bearings with Ford stud pattern) I had lying around gives excellent rigidity to the turret, which has a fair bit of mass to dampen vibrations. At present the three channels used as spindle bases are angling up about a degree or two as I didn't quite get the stub axle at 60 degrees to horizontal, I may fix that up later on. The motor is a 1Hp old school GMF "Cadet" made in Sydney that I cleaned up and fitted a new set of bearings to, it has the dumbell iron pulley on it.

Where I am seeing a potential problem is in the length of the belts required and in the fact that I'd like the motor movement to give a lot of belt slack....I can't see that happening easily with the original plan of the motor moving up and down the column. I may have to try a few motor positions and mounting methods to get it to work, I'd like to avoid an idler pulley for now but that may end up being the easiest option.

Cheers,
Mark

http://www.woodworkforums.com/attachment.php?attachmentid=207639&stc=1&d=1336365103


http://www.woodworkforums.com/attachment.php?attachmentid=207640&stc=1&d=1336365103


http://www.woodworkforums.com/attachment.php?attachmentid=207641&stc=1&d=1336365103

[Stustoys]

Hi Mark,
Things are certainly moving along.
As far as your belt problem goes, have you thought about mounting the motor on a hinged plate. Hinge at the top if the motor is on the front of the post, on the bottom if the motor is at the back of the post.

Stuart

[Graziano]

Hi Stuart, that's pretty much what I'm thinking of doing. For it to all work smoothly I have to lift the belts over the grinder wheels, mops etc. each time I select another spindle. The motor itself if hinged would need to move a fair bit, so If I ran a few short lengths of 25mm RHS off the motor base and then hinged those I could get a fair bit of swing hopefully, then run a pushrod down to a foot pedal.

[BobL]

I assume that only one end of the turrets can hold a wheel and the other will hold a pulley?

If so then this is how I would have oriented the spindles
http://www.woodworkforums.com/attachment.php?attachmentid=207650&stc=1&d=1336372153

The motor could be much higher up so the belt could also be made much shorter and in this orientation will naturally hold its tension better as it is not pulling on the side as in your design.

The arms could also be much shorter as the wheel would be hanging put in the breeze a lot more and be even better accessible. Also a protective shield around the belt might be easier to facilitate.

The arms would either need to be thinner so the belt will not rub on them or wider (or double armed) so the belt could pass through an opening on the arms. something like 2" steel pipe? If this still gets in the way then slightly offsetting the spindles from the arms would be another option.

I agree with Bryan, changing the belt is going to get really tedious. I would even think about using leaving belts on all spindle pulleys so you only unhook the motor end.

[Log]

I assume that only one end of the turrets can hold a wheel and the other will hold a pulley?

.

Hi BobL,
Actually the pulley goes on between the grinding wheel or buff and the bearing housing. I have a couple of old J.D spindle assemblies and on the double ended one, one side of the pulley is used as the inner flange that the wheel(or whatever) butts up against.

Graziano, if you want I can put up a pic of each of the ones I have. You did a great job of the spindle housings/spindles. Once upon a time these spindle assemblies were common in the catalogue's (another word for the spell checker:rolleyes::D), not anymore it seems.

Cheers.

If I'm not right, then I'm wrong, I'll just go bend some more bananas.

[BobL]

Hi BobL,
Actually the pulley goes on between the grinding wheel or buff and the bearing housing.
Ok - I'd still prefer to have the motor around the front, under the arm and keep the belt as short as is practical.

[Ueee]

Hi Mark,
Looks like you have the same "team" working on your spurret as i do working on Freddie.:D Coming along nicely:2tsup:
I like BobL's suggestion of leaving the belts on the spindles and just changing the one on the motor, i think that would make it easier. I would have suggested something with a little more beef than 1hp, but that is what most 8" grinders have so it should have plenty of go still, although there would be more friction in your system than in a normal grinder.

On another note, would you be prepared to cast some mounts up for selling? I for one would be interested. I have one really old similar spindle, but would like a few more.

Ewan.

[Graziano]

I assume that only one end of the turrets can hold a wheel and the other will hold a pulley?

I agree with Bryan, changing the belt is going to get really tedious. I would even think about using leaving belts on all spindle pulleys so you only unhook the motor end.

Hi Bob, I did check out your sketch of suggested mods, that would be a preferable arrangement for a single ended spindle. The pic below shows the first completed spindle unit, so it'll have wheels/mops on both ends with integral pulley/drive washers to keep things compact. I'm certainly going to raise the motor height as high as it will go on the column. The motor will swing in an almost horizontal arc at the end of some hinged 25mm RHS. Having the motor closer, maybe on the front of the column should also bring it's pulley within easy reach for the belt changes, worst case scenario is that I hang three motors on the underside of the channel arms and have fixed belts, although balance could be a bit iffy.

http://www.woodworkforums.com/attachments/f65/205639d1334843484-boring-bronze-casting-actually-size-spindle-complete-1.jpg

[Graziano]

Hi BobL,
Actually the pulley goes on between the grinding wheel or buff and the bearing housing. I have a couple of old J.D spindle assemblies and on the double ended one, one side of the pulley is used as the inner flange that the wheel(or whatever) butts up against.

Graziano, if you want I can put up a pic of each of the ones I have. You did a great job of the spindle housings/spindles. Once upon a time these spindle assemblies were common in the catalogue's (another word for the spell checker:rolleyes::D), not anymore it seems.

Cheers.

If I'm not right, then I'm wrong, I'll just go bend some more bananas.

Geez Log, I though "I" invented the integral pulley-drive washer idea :(. You're right about the spindles once being commonly available, I think a lot of people rolled their own machines like table saws as late as the 1980's. I'd like to see which brand spindles you have on hand, I've pulled apart an old one recently and it was roughly made especially the shaft. I expect the bearing shop that sold it made most of the profit and they were wholesaled cheaply.

[Graziano]

Hi Mark,
Looks like you have the same "team" working on your spurret as i do working on Freddie.:D Coming along nicely:2tsup:
I like BobL's suggestion of leaving the belts on the spindles and just changing the one on the motor, i think that would make it easier. I would have suggested something with a little more beef than 1hp, but that is what most 8" grinders have so it should have plenty of go still, although there would be more friction in your system than in a normal grinder.

On another note, would you be prepared to cast some mounts up for selling? I for one would be interested. I have one really old similar spindle, but would like a few more.

Ewan.

Hi Ueee, this weekend I was feeling energetic so I really went to town on the job instead of thinking about it all day. The motor I have is nameplate rated at 1Hp but the manufacturers in Australia used to cheat a bit in those days: I know for a fact that Crompton Parkinson for example used exactly the same frame, rotor and windings for their motors from 1Hp to 3Hp. The only difference was the current rating of the circuit breaker, by changing the overload breaker to a higher current you got the more powerful motor. I don't know for sure my GMF is the same way though.

As far as selling raw castings go, I'll have to have a think about it and work out a cost for one. The bronze unit is very heavy about 4-5 kilos, I'll have to weigh the second one and see, so for the current price of bronze at $15 per kilo, that bronze one would have a material cost of $60 without any other costs like labour and gas to melt it. The aluminium ones weigh almost nothing by comparison and the silicon aluminium is actually stronger than bronze by a large margin.

[Log]

Here are the pics of the two assemblies I have.

http://www.woodworkforums.com/members/73752-log/albums/misc/8855-p5070018sm-j-d-spindle-assembly-part-number-3205d.jpg

The double ended one has 3205D stamped on the top surface. Overall length is 250mm. Just a few months ago I looked at this spindle and thought I'll make a left hand nut for it, luckily I have the required 5/8 inch UNF tap available.

http://www.woodworkforums.com/members/73752-log/albums/misc/8856-p5070019sm-j-d-spindle-assembly-part-number-3205u.jpg

The single ended one has 3205U stamped on the top surface. Overall length is 220mm.

Both are pretty well made, I had the single ended one apart a few years ago and there is a steel sleeve cast in at each end of the Aluminium casting, these have then been bored for the bearings. You can just see in the two pics a slight protrusion at each end of the housing, they are the ends of the steel sleeves. I just double checked with a file and a magnet and they are steel.
Any more info needed just holler.
EDIT. Just thought, maybe the steel sleeve goes right through, ie. one piece, good possibility as the sleeve would act as a core.

Cheers.

If I'm not right, then I'm wrong, I'll just go bend some more bananas.

[Graziano]

Thanks, they look a lot better made than the examples I've seen so far. They look about the same size as my 150mm long unit. Having a steel sleeve to cast around would simplify things a lot.

Some cheaper units were simply bored full length and a length of pipe pressed in for the bearing shoulders. the shafts were simply machined at one end for the bearing fit and then end for ended in a three jaw and machined again with no concern for journal alignment.

[Log]

hey where did the pics go in my previous post, someone stole the pics, I'll sort it asap

[BobL]

Hi Mark,
n another note, would you be prepared to cast some mounts up for selling? I for one would be interested. I have one really old similar spindle, but would like a few more.

Ewan.

They are really very nice looking spindles and I'd be interested in some ally ones as well, well at least two anyway.

Now that I see the pulley location that makes it even more of a reason to leave the belts on the wheel end and disconnect at the motor end.

One thing I have already noticed about my flat trigrinder arrangement is that it is possible in most cases to access 2 grinders (ie up to 4 wheels) without rotating the turret which means much less rotation that I thought would be required. This is not as likely to be feasible with a single motor or tilted turret

[Graziano]

I'll mention this here as I'm just passing on sales info to those who are interested rather than actually selling anything:

I spoke to Peter the foundry owner, he's happy to sell raw unmachined aluminium castings for $30 each plus postage. He's got my permission to use my spindle patterns for the pictured spindles in this thread which use the 20mm inner race diameter 6204 bearings. It'll have to wait though until he's doing another casting run. From memory it's certified 2000 series high silicon aluminium so the castings machine nicely but it does erode the tool steel a bit. PM me if you want his contact details and I'll give you his phone number & email.

http://www.woodworkforums.com/attachment.php?attachmentid=207702&stc=1&d=1336398206


http://www.woodworkforums.com/attachment.php?attachmentid=207703&stc=1&d=1336398206

[Dave J]

I haven't commented in this thread yet, but have been watching your progress. Your doing some great work there and some good ideas.:2tsup:

Keep up the good work.

Dave
PS
Those castings look nice, and I don't think that is a bad price.

[Graziano]

Thanks for the encouragement Dave, on another note 2000 series aluminium is apparently copper based, will find out today what alloy is used in the castings.

[Graziano]

For those who are interested in rolling their own spindles, Peter dug up a sample of a larger casting also available for $45 which was originally made for imperial bearings and a one inch shaft but which should easily take a common 25mm shaft bearing. This casting is actually easier to machine than my smaller version as there's no rib along the bottom for an oil sump. It's designed to be clamped in a 3 jaw chuck and bored at one end to bearing size, then you machine a couple of "Witness" marks on the outside and then remount in the chuck and check alignment using the witness marks before boring the second journal.

I've seen this particular casting used for 300mm grinder wheels, with a taper on both ends of the shaft for buff mops and also as a 12" disc sander and 2" belt linisher unit.

I'm including a sample of my casting to indicate relative size between the two.

Cheers,
Mark

http://www.woodworkforums.com/attachment.php?attachmentid=207808&stc=1&d=1336476245

http://www.woodworkforums.com/attachment.php?attachmentid=207811&stc=1&d=1336476245

http://www.woodworkforums.com/attachment.php?attachmentid=207809&stc=1&d=1336476245

[Graziano]

It's been a busy week but I found some time on the weekend to work on the project and mount the motor, this time round the front of the column. The motor gets lifted by a cable up the column along two slides made from 25x25mm angle, the cable is run over two pulleys up top and then connected to a foot pedal. It all sounds a bit complicated but gives 40 cm of motor travel up and down the column. There's a fair bit of belt slack which makes it possible to fit and remove the belts from the spindle with one hand if you keep the belts on the motor drive pulley. The turret locking mechanism still has to be fitted but I'm happy with it all so far and there's room to modify things if it proves difficult to swap belts.

Still can't think of a good name for it yet....tried combining turret and spindle in a different way to arrive at: "Turdle" which I'll save as a name if the whole thing proves unworkable as a concept :rolleyes:.

Motor is down in this photo pulling out any belt slack.
http://www.woodworkforums.com/attachment.php?attachmentid=208315&stc=1&d=1336915677


Pedal depressed to raise the motor and slacken the belts.
http://www.woodworkforums.com/attachment.php?attachmentid=208316&stc=1&d=1336915677


Belts come on and off easily with one hand.
http://www.woodworkforums.com/attachment.php?attachmentid=208317&stc=1&d=1336915677

[Ueee]

Nice work Mark:2tsup:
I reackon the biggest pain will be the fact that you have two belts to move and not one. I know you made the pulleys out of weights, which limited your options, but why not just go for a single A or B section belt.
I still like the name Spurret, certainly turdle only brings one thought to mind........

Ewan

[Graziano]

Hi Ueeee, the M section belts have a much smaller recommended bend radius than the A or B section belts. Belt life goes down very drastically if you exceed the recommended bend radius. So using the M section belt lets me use a smaller pulley but I need two to transmit the power.

Edit: So for some higher speed wheels I can get the required RPM with a much smaller pulley than the ones made so far (90mm dia).

[BobL]

That sure is an interesting build there Mark.

Here is an alternative to the cable lift for the motor.
http://www.woodworkforums.com/attachment.php?attachmentid=208319&stc=1&d=1336917950
This means no cables or pulleys, just linkages

[Graziano]

Hi Bob, I studied your suggestion for a minute and I reckon I can get that to work. The current setup's main advantage is that it's adjustable by varying the cable length, you raise or lower the foot pedal and change stroke you can get. In the photo I'm using small G clamps to lock the cable at the motor end as I needed to position the motor along the post to suit the belt length. It's not good practise for the bearings to do so, I may move the spindle pulley outboard of the grinder wheels as that would allow an even shorter belt as it doesn't need to clear the wheel when slack. In a perfect world the pulley would be dished out enough to allow the belts to sit right over the bearing and housing.

I ended up needing only half the 40cm+ slide travel for those 55 inch belts as the pedal is below horizontal: once I'm happy it all works and I don't need to increase the belt length, I can modify to your suggestion and maybe change the pivot point to increase the leverage, say 2:1 (40cm pedal to 20 cm motor movement) to lighten the effort of moving a cast iron motor up and down.

[BobL]

Hi Bob, I studied your suggestion for a minute and I reckon I can get that to work. The current setup's main advantage is that it's adjustable by varying the cable length, you raise or lower the foot pedal and change stroke you can get.
You could adjust the extent of the motor lift with my suggestion by changing the centre of rotation of the pedal. To do that, the pedal arm and the arm that is welded to the upright would need a series of co-centric holes drilled along their length and you could just move the rotational axis to the pair of holes that corresponded to the amount of travel you need.

A complete alternative to the pedal is to lift the motor up to its maximum height under the the turret arms and fix it to the column. Then place the spindles on separate rotatable/lockable bases - like I have on my turret. To slacken the belt you would just loosen and rotate the base and spindle slightly. With suitable stops, the bases could be prevented from rotating too far so a loose base would not permit a rotating wheel to strike its turret arm. This arrangement has the advantage that it uses a short belt and is relatively simple.

I still think changing belts will be a nuisance. I just think of the number of times I have to do it on my DP and keep thinking I must put a VSD on that thing. :D

[Graziano]

:2tsup:
You could adjust the extent of the motor lift with my suggestion by changing the centre of rotation of the pedal. To do that, the pedal arm and the arm that is welded to the upright would need a series of co-centric holes drilled along their length and you could just move the rotational axis to the pair of holes that corresponded to the amount of travel you need.

A complete alternative to the pedal is to lift the motor up to its maximum height under the the turret arms and fix it to the column. Then place the spindles on separate rotatable/lockable bases - like I have on my turret. To slacken the belt you would just loosen and rotate the base and spindle slightly. With suitable stops, the bases could be prevented from rotating too far so a loose base would not permit a rotating wheel to strike its turret arm. This arrangement has the advantage that it uses a short belt and is relatively simple.

I still think changing belts will be a nuisance. I just think of the number of times I have to do it on my DP and keep thinking I must put a VSD on that thing. :D

Fair suck of the mango Bob, lets not totally rebuild the machine yet! :o. I'll give it a go as is before doing any serious modifications: I expect some technical problems like vibration or belt flap but if the layout or setup really bothers me I'll make the necessary changes :2tsup: .

[Graziano]

So no takers for "as cast" aluminium spindle castings of any kind?......fair enuff.:rolleyes:

[BobL]

:2tsup:

Fair suck of the mango Bob, lets not totally rebuild the machine yet! :o. I'll give it a go as is before doing any serious modifications: I expect some technical problems like vibration or belt flap but if the layout or setup really bothers me I'll make the necessary changes :2tsup: .

Sorry mate, it's just that ideas come into my head far faster than I can execute them :D

I'll be interested to see how the final Mark I version works and what sort of column lock you come up with.

Cheers

[Stustoys]

Hi Graziano,
Coming along(unlike most of my jobs lol)
Have you thought about some sort of pin behind the motor pulley to stop the belts falling off while you are changing spindles?


Stuart

[Graziano]

Hi Graziano,
Coming along(unlike most of my jobs lol)
Have you thought about some sort of pin behind the motor pulley to stop the belts falling off while you are changing spindles?


Stuart

Hi Stu, I had been thinking of a couple of discs either side of the pulley that are larger in diameter if it became a problem, I've played around with pulling the belts off and on the pulleys one-handed and it's pretty straightforward: you just hold the belts in your right hand and plonk them on the top of motor pulley and pull them towards you until they are tight, then over the 250mm silicon carbide grinder wheel and on the spindle pulley. As you take your foot off the pedal the pulley grooves are enough to guide them until tight.

A problem I have identified is getting the belt off if there is a grinder tool rest and wheel guard fitted: I easily can fix this if I have the spindle pulley on the outside of the grinder wheel. The alternative is a tool rest that slides sideways to clear the wheel. I guess it all comes down to this: is it better the have the grinder wheel closer to the spindle bearing or to have the pulley closer to the bearing?. The shaft is the recommended 20 mm diameter according to the Norton grinder wheel handbook.

[Graziano]

Had an interesting development today when I went for a walk: there's an unused stretch of road nearby that local arseholes use for a garbage dump. I spotted a fold up pram and an exercise machine dumped there today (I wonder what story they told: an ex boyfriend/husband dumped it?). Anyway I knew that exercise machines have a decent sized permanent magnet motor usually and this one had a 1.75Hp continuous rated motor. Now the motor is rated at 100 to 130 Volts D.C.......normally this would be a problem except for the fact that I design and manufacture 240 Volt AC to 180 Volt DC motor speed controllers as part of my daily bread :2tsup:. A while ago I'd built a prototype 240 to 180 Volt pulse width modulator controller with a 60 Amp peak capacity for a job that never came through, so I have the prototype lying around for that rainy day, i.e. today. The only problem is the motor is air cooled with a fan drawing air through the motor, so a remote ducted intake would be needed to prevent grinding dust intake.

This is a compact, low profile motor and with a speed controller I can rev it from say 60 R.P.M. to at least 50% over speed. This will be perfect for buffing at low RPM or a higher speed for small diameter diamond wheels and it's rated at 1.75Hp continuous.:D

http://www.woodworkforums.com/attachment.php?attachmentid=208509&stc=1&d=1337068312


http://www.woodworkforums.com/attachment.php?attachmentid=208510&stc=1&d=1337068316

[BobL]

Well you clearly have much better " local arseholes" than we do around here.

What a great score but as you say I don't think it will last without an external air supply.

[Graziano]

There's not much to show for it photo-wise but I've been making some progress on the Hexagruff/Spurret. It's now set up to run one spindle via the AC motor mounted below, I think I'll hold off on the DC motor for now until the MkII unit gets made. I capped off the top of the steel post with some 12mm steel so as to have a rigid base to attach the turret locking mechanism which is also made from 12mm steel ( I get laser offcuts cheaply ). At present I can rotate one arm into position and then use a small G clamp to lock the hub from rotating.

So far it's all going to work fine, though some things have come to light: the turret part needs to be accurately made in terms of angles of the channels relative to each other and the angle off horizontal. I cut the angles using a small engineer's protractor to mark out then cut freehand with an angle grinder. If I'd spent more time than I did jigging and tacking the channels at uniform angles from horizontal and vertical it would save aligning and mounting of the spindles later on: even a small error of a degree or so can make a difference. To align the stub axle that the turret spins on I had to cut the column and reweld with a slight lean forward to bring each of the three arms closer to level when swung into position. If/when I do it all over again, I'll make the three armed turret first and assemble it with the stub axle then tack weld into the correct position for final welding.

The sliding motor mount isn't rigid enough on it's own and I need to use a couple of timber wedges to lock it into position so the pulleys stay in alignment, while I can't ensure the motor and the spindle shaft are parallel to each other, I can get the pulleys in the same plane of alignment though there could be a slight "twist" relative to each other. The motor is going to get a new hinged mount now that I know where it needs to be and how much it needs to move. It should be possible to use the other side of the pivot point to pull the spring loaded turret locking pin with a short rigid arm or cable.

I do notice the motor has it's shaft centre drilled and accessible and I reckon I can make a simple alignment jig to clamp on to the motor centres at one end and clamp on to the spindle centres at the other end. This would allow me to drill each of the four spindle mounting holes with the spindle locked parallel to the motor.

The one spindle I have fitted runs with some vibration as the wheels aren't trued yet, the vibrations damp down a lot at the stub axle hub which is so stiff and rigid it readily transmits vibration to the column. At the spindle end of the arm a glass of water jump off from vibration, at the stub axle end of the arm it just sits there with a ripple. The belts have about a 2 cm flap every few seconds on some harmonic interval, I'm hoping the hinged motor mount combined with a tension spring or gas strut to get belt tension will dampen vibrations further than the current setup with the motor wedged to the column........phew! :whip:

http://www.woodworkforums.com/attachment.php?attachmentid=209044&stc=1&d=1337477867

[Retromilling]

Incredible , very Leonardo da Vinci in flavour.

[Graziano]

Incredible , very Leonardo da Vinci in flavour.

Heh, over the years things I've done have been compared with a lot of other things.......but this is the first time it's been Leonardo Da Vinci :D. There has been some earlier tri-grinder units including Bobl's version with three bench grinders.

[Stustoys]

Hi Graziano,
Perhaps fix the motor to the column and use another pulley to tension the belts?

Stuart

[Graziano]

Hi Graziano,
Perhaps fix the motor to the column and use another pulley to tension the belts?

Stuart


NNNnnnyyyyeahhhmaybe, I need to make a lot of slack on the belts to get them over the grinder wheel and threading them over three pulleys instead of two could be harder to do. Even longer belts would be needed too.

If the hinge pivot is about 90 degrees above an imaginary line drawn from the spindle shaft to the motor shaft the motor should swing towards the spindle the absolute minimum 20 cm required. The motor would also be able to swing towards the spindle against springs if the belt tension varies a bit, the motor wedges I use at the moment couple the belt vibration to the column.

You know Stu, I am just implementing your motor mount suggestion from post No.11 :rolleyes:

[Stustoys]

You know Stu, I am just implementing your motor mount suggestion from post No.11 :rolleyes:
Yes :D
I certainly like that idea better, as long as the belts dont flop around to much.

Keep up the good work

Stuart

[eskimo]

Yes :D
I certainly like that idea better, as long as the belts dont flop around to much.

Keep up the good work

Stuart

I was thinking the same/similar Stuart...long distance between drive pulley and driven pulley coupled with no real support at or under mounting area of spindle could lead to lots of vibration as well as belt slap which may compound the... err my ....vibration theory???

but running under load will prove it one way or another

[Graziano]

I was thinking the same/similar Stuart...long distance between drive pulley and driven pulley coupled with no real support at or under mounting area of spindle could lead to lots of vibration as well as belt slap which may compound the... err my ....vibration theory???

but running under load will prove it one way or another

It's currently got 2cm of belt flap with a regular time period of about 2 seconds, the pulleys have a reduction ratio of 1:1.1666666 so I wonder if the slight ratio difference gives it a harmonic like that. The reason is that years ago I built a 1Hp disc sander with a 2:1 pulley ratio and a very long belt as the motor was at floor level and the disc at waist height. A friend with some experience in making them said I'd have trouble with belt flap and said he had to use a rigid backed "Pump" belt to stop his from flinging off when stopping. Anyway my sander had no hint of critical speed flap on startup or much running vibration at all :o, it just sat there quietly with the disc hissing from the airflow. My friend muttered something about me being arsey but I can't help but think the 1440 rpm motor and two different sized pulleys really helped prevent vibration and eliminate the critical speed belt flap.

[eskimo]

I would think that having the belts at 90 degrees to the mount would increase movement at the spindle and hence give vibration which in turns compounds the belt slap and one assists the other gradually increasing to its limit

even small irregularities in the V belt..hard/soft spots on the belt (usually on the cheaper belts) can result in increased vibration and once it starts other things can compound the effect.

Going to A section or B section may not be the answer...going to SPZ and keeping the distance short between driven and drive pulley can help reduce vibration..only problem with SPZ's/SPA's are that they like to be very tight so mounts but be rigid...or vibration will once again set in???

[Graziano]

I would think that having the belts at 90 degrees to the mount would increase movement at the spindle and hence give vibration which in turns compounds the belt slap and one assists the other gradually increasing to its limit


I'm hoping to avoid that with a 90 degree mount by using spring dampening/tension to begin with and maybe later with a gas strut to provide tension but allow some slight movement for belt unevenness. One option that might work best to release the belt tension would be an over centre brace to give a rigid locking action.



Going to A section or B section may not be the answer...going to SPZ and keeping the distance short between driven and drive pulley can help reduce vibration..only problem with SPZ's/SPA's are that they like to be very tight so mounts but be rigid...or vibration will once again set in???

That reminds me, on the smooth running disc sander, the motor mount was rigid, it was hinged with a threaded rod to adjust belt tension. Even so I've seen a spindle with a rigid motor mount that only has a 24 inch A section that continuously flaps on the driven half of the belt not the returning/retreating half. The whole thing is rigid and solid yet the short belt flaps like a guitar string.

[Ueee]

I'm hoping to avoid that with a 90 degree mount by using spring dampening/tension to begin with and maybe later with a gas strut to provide tension but allow some slight movement for belt unevenness. One option that might work best to release the belt tension would be an over centre brace to give a rigid locking action.

Hi Mark,
I have always has belt flap with multiple belts, first one and then the other belt, sort of copying each other. Never real bad though. I had always thought that a rigid mount was better than a sprung mount in regards to belt flap. I have found with sprung mounts the torque of the motor always moves the mount on startup, which can throw belts off. With the belts flapping, the spring can allow the motor to move and cause more flap, etc etc.

Ewan

[eskimo]

I'm hoping to avoid that with a 90 degree mount by using spring dampening/tension to begin with and maybe later with a gas strut to provide tension but allow some slight movement for belt unevenness. One option that might work best to release the belt tension would be an over centre brace to give a rigid locking action.



That reminds me, on the smooth running disc sander, the motor mount was rigid, it was hinged with a threaded rod to adjust belt tension. Even so I've seen a spindle with a rigid motor mount that only has a 24 inch A section that continuously flaps on the driven half of the belt not the returning/retreating half. The whole thing is rigid and solid yet the short belt flaps like a guitar string.

short belts are or can be a problem ...as I said above going to SPZ/SPA's commonly called wedge section (they have a deeper V than equivalent counterpart) may (if mounting does not flex) overcome flap, but they need to be very tight..and I mean tight, whereas if you tightened a standard A section to same it would be too tight and belt will prematurely fail.

[Graziano]

short belts are or can be a problem ...as I said above going to SPZ/SPA's commonly called wedge section (they have a deeper V than equivalent counterpart) may (if mounting does not flex) overcome flap, but they need to be very tight..and I mean tight, whereas if you tightened a standard A section to same it would be too tight and belt will prematurely fail.

Thanks I'll switch to the SPZ's after the other measures have been tried. At this point the belt flap is what I'd consider acceptable with the motor rigidly wedged but I want to switch to the hinged motor to make the pulley alignment more accurate and rigid than the slide setup currently has.

[Graziano]

Not too much work has been done on the Spurret lately, I did fit a gas strut from a photocopier document feeder lid to keep up the belt tension (slight blurred top belt in picture): it was very effective at reducing belt flap and vibrations but the stroke could be longer. I showed it to a guy with more experience in these matters and he replied "Jesus &*$"£! $"*&%!! just how smooth do you want this thing to run??". The strut made the sliding motor mount practical to use as it dampened a lot of the vibrations while still allowing the belt tension to be loosened off for a spindle change. I do plan however to make the motor fit a couple of hinged arms as it would make the pulley alignment much more accurate and could allow a hinged brace for the spindle arm...possibly

http://www.woodworkforums.com/attachment.php?attachmentid=213194&stc=1&d=1340181097