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Faceplate turning speed.

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Forum topic by ashahidan posted 01-24-2012 05:39 AM 2235 views 0 times favorited 12 replies Add to Favorites Watch
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ashahidan

64 posts in 2558 days


01-24-2012 05:39 AM

Topic tags/keywords: question

What is a safe speed for turning a 7 inch diameter wood blank on the lathe face plate?

Ii it safe to use turning tools made from steel files?

-- asm


12 replies so far

View richgreer's profile

richgreer

4541 posts in 2534 days


#1 posted 01-24-2012 05:51 AM

With respect to safe speed – it all depends on how well balanced the piece is. When you start with a rough piece of wood it will almost always be out of balance. You probably need to get down to a pretty slow speed (600 rpm). As the piece gets rounder and more in balance, pick the speed up. I would probably work up towards 1600 when the piece is in good balance.

Regarding turning tools from a steel file – - I simply don’t know, but I would probably be willing to try it. Make sure to wear a face mask, just in case it flies apart.

-- Rich, Cedar Rapids, IA - I'm a woodworker. I don't create beauty, I reveal it.

View David Kirtley's profile

David Kirtley

1286 posts in 2457 days


#2 posted 01-24-2012 07:59 AM

Carbon steel is fine as long as you are cutting and not scraping. Temper the metal and it will be less brittle and won’t break. Of course it won’t stay sharp as long. I would go to a light purple/gold for that. A really light straw will be too brittle. If you don’t know what I am talking about, it is time to study up a bit on heat treating metal. If you have not seen the colors, practice on some scrap first to see what to look for. Heat the metal to red hot (Real test for temperature is that it is hot enough when a magnet won’t stick to it. With practice, you can tell from color.) Quench it. (I would suggest using a can of oil to start. Water and brine are not as forgiving and can warp and crack easier) That will make the steel glass hard. In that state it is brittle. Now, clean off the scale from the metal to shiny steel. As you heat it back up slowly, it will start changing colors. It will first turn a light yellowish then darken and the color will change to purple then blue. Each of the colors is different hardness. The light yellow (usually referred to as straw yellow) is really hard like you would want a chisel. As you get softer, it also gets springier and less brittle. Springs get tempered to blue. What you will want is one of the colors in between. You can also toss the steel into the kitchen oven to temper at about 425F-450F for an hour or so (Watch for color changes). For getting the steel soft to shape it, you anneal the metal by getting it red hot and then letting it cool slowly. The more slowly you cool it, the softer it will be.

When you start out turning, if the piece is really out of round and unbalanced, whack some off. A drawknife or hatchet is ok. Pre-rounding it a bit on a bandsaw is a good way as well. As far as the speed, start out as slow as you can go. When it gets round and more balanced, you can speed it up. There is no real answer as to the speed though. Depends on how you are cutting and how far from the center you are. The wood near the axis of rotation is not moving very fast at all. Out by the edge it can be moving a lot faster. In general, at one inch diameter at 500 rpm, the wood is moving past the cutter at about 1500 inches a minute. At 7 inches, that translates to 10,500 inches of wood going past every minute (7 times as fast). It is going to be by feel for the most part. If the chips are building up on the cutter, you are going too fast. If you hear anything that sounds like cracking or it feels like it moves, stop immediately.

-- Woodworking shouldn't cost a fortune: http://lowbudgetwoodworker.blogspot.com/

View Tootles's profile

Tootles

780 posts in 1961 days


#3 posted 01-24-2012 10:31 AM

I recently came across a rule that says that when you multiply the diameter (in inches) by the spindle speed (rpm) the product should be within the range 5000 to 8000 – at the lower end for roughing and the higher end for finer work. So with 7” diameter that works out to a speed range of about 700 to 1140 rpm.

I’m pretty sure that the rule is not absolutely precise, but it could be a good starting point.

-- I may have lost my marbles, but I still have my love of woodworking

View ashahidan's profile

ashahidan

64 posts in 2558 days


#4 posted 01-24-2012 01:49 PM

Thank you richgreer,David Kirtley and Tootles for the answers. I can understand about the speed but I
have too little knowledge about heat treatment. I would like to check with david whether it is possible to
heat treat only the cutting end of the chisel with oxyacetylene. I do not have a forge. And there is no practicing blacksmith around anymore.

Thanks again for all your very helpful answers.

ashahidan

-- asm

View zacker's profile

zacker

5 posts in 2093 days


#5 posted 01-24-2012 03:29 PM

it its really off center but you dont want to lose the grain pattern, either cut some of the excess wood off or spin it very slowly and take it down some with a very sharp chisel. I use the carbide rougher.. the steel handled one with the square, replacable carbid blade. if on a budget, you can very easilly make on and just buy a replacement cutter and put it on, Captain eddie has a great DIY tutoriaL on how to make this on his you tube channel… search you tube for Captain eddie. One of my very first turnings was on my lathe with a chunk of log so out of round the lathe lmost hopped off the stand…lol Oh and if you can cut a tennon right away and ues a four jaw chuck. and if you are useiing a face plate, be sure to run the tail stock tight up to the other side to help keep the blank from flying off.

View David Kirtley's profile

David Kirtley

1286 posts in 2457 days


#6 posted 01-24-2012 03:32 PM

Heat treating is not hard to do. It is just hard to explain.

Oxyacetylene is more than sufficient. It will work fine. I just use a propane torch. You can also use a wood or charcoal fire. Yes, you heat treat different parts of the piece to different hardness quite often. With knives for example, you make the tang a lot softer and more springlike to keep it from breaking. You only need to harden the part that you will be cutting with during the useful life of the tool. The rest you do not want to be hardened.

The hardness and brittleness of the steel is why people are against using files for turning tools. If you leave them too hard, they can break and be dangerous.

-- Woodworking shouldn't cost a fortune: http://lowbudgetwoodworker.blogspot.com/

View richgreer's profile

richgreer

4541 posts in 2534 days


#7 posted 01-24-2012 04:13 PM

I want to respond to tootles about lathe speed. IMO, your rule is a good one at the low end (for when you are starting) and maybe a little slow at the high end.

My lathe has a readout of the RPMs, but I seldom look at it. In my experience, there is a speed that just “feels right” for a given set of conditions. I set my speed based on what feels right and essentially ignore any formulas. b.t.w. – Most of turning is a “feel thing”. You know that you are holding your gouge or skew or whatever right by the way it feels.

Based on my observations of my turning friends, I think I run a little slower than most in the beginning and higher than most in the end.

Of course, part of it is the lathe you are using. If you have to stop and move a belt to a different set of pulleys to change speed, you will change speeds less often than if you can set the speed by turning a dial or moving a lever. I can change speeds by easily moving a lever. Hence, I find I am moving the speed up often, but in small increments.

-- Rich, Cedar Rapids, IA - I'm a woodworker. I don't create beauty, I reveal it.

View hairy's profile

hairy

2384 posts in 2991 days


#8 posted 01-24-2012 04:45 PM

http://www.youtube.com/watch?v=-3mqZjTgVc4

-- stay thirsty my friends...

View ashahidan's profile

ashahidan

64 posts in 2558 days


#9 posted 01-25-2012 10:51 AM

To all friends who have responded to my question.

I would like to tell you I do not have a proper wood lathe. My lathe is a 3inch home-made faceplate attached directly to an electric motor which has a fixed speed of 1450rpm. So I never tried using wood which is not “rounded” first. I attache the wood to the faceplate with wood screws and once or twice the wood just flew off the faceplate. I knew the danger and I never tried turning wood larger than 7 inches in diameter. Right now I just couldn’t afford a proper lathe machine so I have to make do with what I have.

Before attaching the wood to the faceplate I rounded it first with a small Hitachi router.If the wood was too thick for the router I used the jigsaw to round the wood but the problem was that the thin blade do not make a vertical cut most of the time.

I ask about the speed because I wanted to make a lathe for faceplate turning. A friend had donated a rewound one hp motor with a 0.75 inch diameter shaft. I plan to fix a cast iron pulley for three speeds. I will get a steel spindle ,attach two bearing blocks to it and then attach another pulley set to it. I am going to use two blocks of 4 inch square timber, 3 feet long as the lathe base.

Now I have the base,the motor and I have to get some more cash to get the pulleys and the bearing blocks. As the present face plate could not fit the new motor shaft I have to have another one made by a machine shop.

Of course it will involve too much work but it will be very much cheaper.

Turning tools are not available here. So I made my own turning tools from flat files. So far none has broken but the cutting tip became blunt very fast . I did not do any hardening as I did not know how. I will try following the instruction from David Kirtley.

Thank you again to all for enlightening me, an old novice.

ashahidan

-- asm

View michelletwo's profile

michelletwo

2594 posts in 2475 days


#10 posted 01-25-2012 12:35 PM

OK I’m going to come at this speed question from a different angle. Make your own springpole lathe. I did it 30 yrs ago & it worked great. Cost you about nothing. Search youtube and other sites. If you are a woodworker, this will be easy. a 1400 start speed is WAAAAYYY to high to be safe..check yard sales for older tools. you can pick up very very cheaply. Good luck

View zacker's profile

zacker

5 posts in 2093 days


#11 posted 01-25-2012 02:24 PM

@ ashahidan,

I see older head stocks like the one you want to build on Ebay all the time… Most of the parts to make a lathe can be found there, just be sure to get a matching tailstock if you arent making on. You want them to perfectly (or as close as possible) alighned so your spindle spins true (or very close to it..lol) Also, if you are here in the states, Craig’s List has some pretty decent deals on lathes from time to time, it just takes a bit of patience to wait till one comes along. I think you could build one yourself though, it seems like a pretty straight forward thing.. how about for a bed rail, you get a 6×6 piece of wood as long as you want it to be and cut a grooved channel down the length like a big T slot and then you make your tail stock and mount it to a piece of 6×4x3/4” hardwood that has the mating rail under it so it stis in the T slot like a miter for a table saw, so you can slide it back and fourth on the 6×6.. you can lock it down with a couple bolts or something. Just a thought.

View David Kirtley's profile

David Kirtley

1286 posts in 2457 days


#12 posted 01-25-2012 05:18 PM

Here is what the tempering colors look like. It will be a little different looking in real life but this is a good start.

Take a look at woodgears.ca for his bandsaw building information. The bottom half of this bandsaw is a good start for making a faceplate lathe. You can make your own stepped pulley from wood.

For large faceplate turning, you will definitely want to slow down through pulley reduction. It will also increase the torque so you will have more power to turn larger items. If you are going to be turning very large pieces, you want to be able to get down to the range of 100-300 rpm or even slower for really large things like tabletops. Ideally, try to find a way to get variable speed, but don’t worry about it too much. Stepped speed changes are a bother but not that bad.

Once you have one lathe made, you can easily build yourself a better one. The first one is hard.

-- Woodworking shouldn't cost a fortune: http://lowbudgetwoodworker.blogspot.com/

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