Slowing down a wood lathe

[6days]

I have a Carba-Tec 1.1m Wood Lathe and am considering putting a speed controller on it to slow it right down. The controller I’m thinking about is from Jaycar ‘CAT. NO. KC5478 240V 10A Deluxe Motor Speed Controller Kit’.
Has anyone done this, or does anyone have another idea on how to slow this lathe down to about 5-19 RPM.

[Cliff Rogers]

G'day.

You will find that those speed controllers only work with certain types of motor & when they get down to speeds that low, they have no torque & stall easily.

[powderpost]

G'day.

You will find that those speed controllers only work with certain types of motor & when they get down to speeds that low, they have no torque & stall easily.

That has been my experience too.
Jim

[BobL]

What do you mean by 5-19 RPM do you mean 5 to 19 rpm?

Provided you are comfortable doing your own mods and can do it safely the cheapest way to get variable speed on a WW lathe is using a VFD and a used 240V 3 phase motor.
If you have to pay for a sparky to do the mods then that's a financial black hole I'm not prepared to speculate on.

Look here
http://www.woodworkforums.com/f245/bobls-shed-fit-134670/index21.html#post1526051
Post s #309 thru 319.

The slowest speed I am comfortable running continuously on full load is ~150 rpm.
I can go a bit slower for a short time - but not under a high load for very long.

[tore]

I have a Carba-Tec 1.1m Wood Lathe and am considering putting a speed controller on it to slow it right down. The controller I’m thinking about is from Jaycar ‘CAT. NO. KC5478 240V 10A Deluxe Motor Speed Controller Kit’.
Has anyone done this, or does anyone have another idea on how to slow this lathe down to about 5-19 RPM.
That speed control is only suitable for universal motors eg. Handheld drills, angle grinders. With other words motors that have bruches, not asynchronous or inductions motor that is fitted to your lathe

[6days]

The problem I have is vibration from large out of balance pieces, and I need it to turn slow enough to be safe. I’ve done the whole walking lathe thing; even got the shed to shake. Never did get a t-shirt though. The only other solution is to build another lathe but I’m reluctant to do that.

[Paul39]

6Days,

Have a look at this:

https://www.google.com/#q=buy+10+rpm+geared+motor

Depending on how much torque you need, a BIG pulley on the outboard side of the lathe and a tiny one on a variable speed electric drill motor, and a slack belt on the regular motor, might do what you want.

24 inch pulley on spindle & 2 inch pulley on motor gives you 12 to 1 reduction. 1400 RPM motor divided by 12 gives 117 RPM on the spindle. Small pulley diameter divided into large gives you ratio. Check the nameplate speed on your electric drill and calculate accordingly.

[orraloon]

Rather than spend $ on the lathe mods look at ways to balance up the large bowl blanks. I have used an electric hand plane a few times to knock off the high spots before turning. Do not run the lathe as you do this. Mount blank and turn over by hand and the tool rest can be used to find the high spot. Lock index pin and plane off high spot then repeat until things are reasonably balanced. Electric planes can take a quite agressive cut and this does not take long to balance quite large blanks. Reasonably safe too as no large lumps will come flying at you. When you can spin the blank at the lowest speed without too many woobles then you are good to go. I would think this is also a faster fix than roughing down a large out of balance chunk on a really slow turning lathe.
Regards
John

[Jim Carroll]

The problem I have is vibration from large out of balance pieces, and I need it to turn slow enough to be safe. I’ve done the whole walking lathe thing; even got the shed to shake. Never did get a t-shirt though. The only other solution is to build another lathe but I’m reluctant to do that.

The problem with these lathes is they were never designed for bowl turning, but that is what most people buy them for. They have poor electrics and poor mechanics

The original design was for spindle turning but still their high speed of around 2000 is too slow for some applications like pen turning.

Their low speed of 500 rpm is too high for some bowls like yours which is too out of balance.

At their low speed you will also find you have no torque as the belt runs very loose.

Your option is to get the blank onto an bandsaw and try and get closer to round before trying to chase the lathe around the work shop.

Next best option is if you want to persist with bowl turning is to get a better lathe , you can waste a lot of money trying to get this one to work better but at the end of the day you still have something that does not do the job properly

[Paul39]

6days,

You apparently made your second post while I was writing. If this: http://www.carbatec.com.au/images/hires/MC1100A.jpg is the lathe you have, put several bags of sand, concrete blocks, dead car batteries, or buckets of gravel on the bottom shelf.

Do as much rounding as you can with whatever saw you have available.

I have a Hegner 175 which is lighter than yours and the slowest speed is 800 rpm.

See:http://houtdraaienindehaarlemmermeer.nl/active/arie/shoparie_1.jpg

Most of what I make bowls from are logs, stumps, and roots. I cut the corners off with an electric chain saw and center the blank on a face plate covered with plywood and bring the tail center up. I spin the blank by hand a few times and if it keeps coming to rest with the apparent heavy side down, adjust a bit. I then tighten the tail center while spinning the blank by hand and lock it.

I stand to the side and turn on the lathe at the slowest speed, keeping my hand on the off switch. If too much vibration I shut down and adjust. If it is within my pucker factor I put on the face shield and taking light cuts knock off the protruding parts. I turn off the lathe and have a look and move the blank slightly to center it better. More light cuts and have another look with lathe stopped.

If the blank is in position for the bottom of the bowl I re-tighten the tail center and make a spigot or recess for the chuck and do the contour of the bottom, take it off the lathe, put on the chuck, and grab the bowl by the spigot or recess, hollow, scrape inside and out, sand, and finish.

If the blank is top side out at the end of the first roughing, I'll make it flat, leaving the least knob for the center to hold it on the face plate, take it off the lathe, cut off the knob with a bench chisel, put the flat against the face plate and center, bring up tail center, and proceed as above.

I usually just count on friction and pressure from the tail center to keep the blank on the lathe at first. I do have some face plates with sandpaper glued on them that I grab with the chuck, and I have put 3 - 4 nails into the plywood and cut them off to to about 1/4 inch to grip the blank better.

When I first begin with an out of balance blank I stand toward the tail stock end, out of the way of a blank coming out of the lathe. I have had a few come out in 5 years. One was screwed to a face plate with 4 #10 screws and the tail center up tight. This was an interrupted cut on my 20 inch Woodfast with a hard as stone piece of stump. I had a bad catch and the blank broke 2 screws and tore out the other two and went sailing 20 feet out into the yard.

All of the above contributors advice about round balanced blanks, and how to get them is very good.

[6days]

Thank you all, I think I’ll just have to bite the bullet and make a lathe that suits my needs.

[DonIncognito]

Thank you all, I think I’ll just have to bite the bullet and make a lathe that suits my needs.

At least try to stabilise the base first. Go to your locally owned hardware store, get two or three bags of the cheapest cement possible and stack them on the lower shelf. Set you back an hour or so plus $50 or $60, and if you dont like it, you can return the cement and swap it for wood for your new lathe stand.

[6days]

Mt last post was before the last few posts were made about using an electric planer etc. I will try this although my lathe doesn’t have indexing I’ll figure some way of stoping it turning while I shave the wood off. Thank you for the advice.

[Paul39]

Mt last post was before the last few posts were made about using an electric planer etc. I will try this although my lathe doesn’t have indexing I’ll figure some way of stoping it turning while I shave the wood off. Thank you for the advice.

Make a long wedge of wood and slip it between the blank and the bed of the lathe.

Do not be in too much of a hurry to abandon your existing lathe. I have been assembling parts for my monster bowl lathe for 3 years or so, meanwhile making and selling over 100 bowls on my "inadequate" lathe.

If your lathe is the one I found and posted in my post above, it is a decent workable lathe. There is no perfect lathe.

If you are just beginning to turn bowls, you may want to make some 200 - 300 mm to get the feel of bowl turning. That size should not make the lathe vibrate much.

[dr4g0nfly]

I personally can't see how you'll cut the timber at such low speeds. 5 - 12 rpm, the torque you'd need is hugh, such that you'd not be able to hold the tool, and the tear out would be awful.

I've seen an American turn at these speeds but he did not use hand held tools, he had a Router held in a 2 axis bracket system (no up & down) to cut the wood.

[Ed..]

It may have been mentioned before or not, but as it is late I haven't had time to read the entire thread properly. Having said that I have just recently built myself a largish wood lathe with a 4HP induction 3 phase motor and 2 step pulley and a VFD to controll the RPM in both ratios, using the the VFD to drop the speed also results in significant drop in torque as well to the point that if I drop the speed down too slow ie; 60 RPM you can actually stop the motor by hand. Also the more mass your lathe has, the less it will want to "walk" due to imbalance. I think that mine is about 400-450Kg so it takes a lot to vibrate, but nothing is immune, give it a big enough, heavy, out of balance log at too high a speed, and mine will do the same. I just don't want to be near it if that happens.

Torque is a function of a motor running at its designed RPM, the more you electronically/electrically drop the RPM's the less torque you have. The only way I know to actually increase the torque and at the same time drop the RPM's so your out of balance wood doesn't shake it self to bits or damage the lathe, is to use lots of step pulleys, as in like the metal lathes do or your cars transmission.

As the previous poster mentioned you might be able to mount a router on some sort of frame and when the wood revolves underneath it, it will take out the high spots and you won't have a problem with low torque as the router will be doing all the work and the lathe just turning slowly, (once you work out how to slow it down), and which is what I am planning to do for mine in the future. . VFD's don't work on all type of motors from what I have been told. There are some video's of the router setups on youtube. Just my 2 cents worth.

Cheers

Ed.