I need to replace the spur on the headstock of my Jet lathe. I read tonight that 4-prong spurs need a pretty flat surface, and 2-prong spurs can meet up with uneven surfaces (paraphrasing). Should I get both, or can I get by with just the 2-prong?
forestgirl — you can take the girl out of the forest, but you can’t take the forest out of the girl 😉
Replies
Jamie,
You can get by with 2 prong but it also depends on what you are turning, the type of wood, how heavy handed you are and how many fatal catches you have (;).(4 prongers grip better)
I like a 2 prong because usually they are small diameter and one could want this when turning small diameter stuff.
I wouldn't have thought the uneven surface thing would be an issue- one is supposed to cut the billets off reasonably square, surely?
Phillip, you will see some of the bowl turners start out with a blank that has not been prepared at all. They are essentially straight from the tree.
Steve
To me, and I'm not an expert here, if you are starting with a very unprepared blank, I'd think I'd want the most holding power I could get since the blank will be unbalanced. Also remember that with a 2 prong, you need enough "preparation" to see the grain direction, since you don't want the spur to turn into a splitting wedge. To that end, the 4 prong makes sense to me.
Steve, you have missed the point of my reply to Phillip. I wanted to let him know that not all turning begins with billets that are 'reasonably square'.
Steve
My comment about 4 v. 2 prongs was based on a brief scan of David Ellsworth's book at Barnes and Noble yesterday. Makes sense in an intuitive way to me, but I've not discussed it with experienced turners. Just guessing, the thing about 4 prongs is that when you're trying to tape the spur into uneven stock (on the table, not mounted in the lathe), there are just too many spurs to deal with. On the other hand, the stock is under quite a bit of pressure on the long axis, once the head- and tailstock are brought together. In stock that's the appropriate size for a spur, I'd think 2 prongs would hold well.
In the class, I had one piece of stock that was freshly-gathered Madrone, just cut into lengths, maybe 1.5" D. Ends weren't finely cut, and it was a challenge (for a beginner) to figure out how to mount it in the lathe. But once it was there, it was solid. It became symmetrical quickly under the roughing gouge (cool feeling!).forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
Thanks, Philip. I'm going to be working on pretty small stuff the first few weeks. I'd guess the biggest dimension of the rough stock would be 2.5 inches. Not planning on any big catches -- in fact I'll spend alot of time practicing technique to perfect the safe stroke with the chisels. Doesn't bother me to invest that time, especially with the skew. She gave us the exact info we need to use it safely, and we worked for awhile just practicing the technique.
This is definitely an activity that won't be done when tired!forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
I would recommend the 4 spur of the 2 options mentioned. Even if all 4 spurs are not set to the same depth on an uneven blank the grip is good. Even better are the Stebecenters. A bit expensive but grip well and very safe if you have a big catch. Penn State also has a version of this but I have not used theirs.
Bruce
Hi, Bruce. I've looked at the Stebcenters and the PSI version. I'm sure I'll get one, but for now I'm just going to get a regular spur. Regarding the safety of the Stebs, it seems important to me to note that they give way in the case of a catch only if they are engaged lightly, at least according to the description on the linked page.
When I first heard about them, I thought there was something magical that kept them from catching, period. What I like most about them is that they won't split the wood.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
Hi F.G. Buy a drive centre that has interchangable heads,2,4spurs ,6 needles, a cone and in various diameters.Then all you need is a steb,hollow cone,screw chuck .By the time you've bought a good chuck or two the price of the lathe is small change . Besides turning is fun and I am convinced it balances the the intensity and uptight of cabinetmaking in me ;-)
Edited 10/1/2009 9:32 am ET by jako17
Thanks, Jako, I'll check out the interchangeable arrangements. The spurs I'm looking at are from PennState, and not expensive, so I may just grab one for now, go for more versatiilty later. Depends on the relative expense. Having just dumped over $500 on class, travel, hotel and turning tools, I need to keep things a bit austere for a month or so.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
Actually I had forgotten that FG is "bowl turning orientated " at the moment ie the emphasis is not on spindle turning as far as I know.
To me prong centres are for spindle turning ie between centres, and turning chunks for bowls is best done with something that grips as well as drives-so no need to turn for a tail centre.Philip Marcou
Ooops, Philip, nope -- not "bowl-turning oriented" at this time. My first turning class was conducted in spindle-turning mode, which seems to be a good way to introduce total newbies to the safe use of chisels on a lathe, practice cutting shapes, etc.
I definitely want to turn bowls not too far down the road, but for now, I have several things I want to make that are in spindle-turning mode.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
Hi Philip, Surely f.g . is currently obsessed (if not, soon will be, as turning is very addictive) to spindle turning hence the disscussion on drive centres.With regard to a tail centre; it is a very good safety feature to use one when rough shaping a large bowl blank.Even when chucked.Saves rearranging ones facial features when the blank goes into orbit.Lastly I use a 2 prong centre and tail centre to turn the dovetail on bowl blanks before chucking.
Do you feel that having the tailstock engaged when rough turning a bowl mounted on a screw-center faceplate adds any security? I've had blanks fly off chucks, but I feel pretty safe with a screw-center faceplate, or faceplates in general.Screw-center faceplate, for those unfamiliar:
http://www.woodturnerscatalog.com/store/Lathe_Accessories___Screw_Centers___Faceplates___Screw_Center_Chuck___screw_center_chuck?Args=Chris @ http://www.flairwoodworks.com and http://www.flairwoodwork.spaces.live.com)
- Success is not the key to happiness. Happiness is the key to success. If you love what you are doing, you will be successful. - Albert Schweitzer
I have a screw centre but seldom use it for roughing out bowls.My usual method is a large 2 prong centre driven in with a mallet and a livecentre in the tailstock.With long grain hollow forms made from a crotch (therefore wildly out of balance )I use a chuck with jaws that expand into a 1 inch hole and the tailstock.For large newels where the blank is 7"square by 42"I use the same set up.Like most woodworking whatever works for you.If you get that nasty feeling back off and think, are you in the way of a missile? A friend in the UK has a large hole in his shed roof from a bowl blank. Have fun and aviod missiles!!!!!
I suppose in that regard, my midi lathe with a 10" swing keeps me safer. To get a max-sized bowl, I cut all my blanks round on the bandsaw first so they are well balanced. But I do want a bigger, bowl-turning lathe (no tailstock). I have a dream...Chris @ http://www.flairwoodworks.com and http://www.flairwoodwork.spaces.live.com)
- Success is not the key to happiness. Happiness is the key to success. If you love what you are doing, you will be successful. - Albert Schweitzer
Fellow woodturners.. Just a point of safety on using the tailstock even when using a faceplate. I find it gives a bit of extra safety and comfort to use the tailstock whenever possible, even with a good face plate while you turn a tenon for the chuck (I've got a couple of dents in the cabinets from past experience). I endeavor to do as much as I can to completly finish the bottem of a bowl and at least half way up the sides before flipping it over in the chuck and doing the inside and the final finish. Then using a set of bowl jaws flip it back over and finish the bottem cutting the tenon at very slow speed with final power sand and finish. Its a little extra but as all bowl turners know the object is to finish the bottem so they can't tell how you held on to it while turning. Ever seen a fellow bowl turner pick up your work and instantly turn it over to see how it was held?? FG.. nice to see you turning again..as for spindle turning, try some pen making. Very inexpensive to get into and quick results in 30 minutes or less to finished product. Always scraps around and selling pens that cost you about $3.00 - 5.00 to make for $25-40 really helps pay for the other stuff...all the best
I'll keep you advice on file for when I get to bowls (not too long, I hope). A friend just offered me some tool rests from his 1236 that don't fit his new lathe, so I'm ahead of the accessory curve now.
Re: pens. I kinda figured there were already too many pen turners in the world. No? I'll have to try a couple for fun. They don't grab me at first glance, but obviously they could be addictive once tried, since they are turned, LOL.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
Oh, I'm obsessed, not doubt about it. Not just with spindle-turning-type stuff, though, that's just where I'm going to start. Turning may be what brings woodworking back into my life on a daily basis. Since I started working with the horses again, I've not been able to fit WWing in very well, but turning seems like something that I can go out and do for an hour or so, finish a project in one or two sessions. And I like how "organic" it seems. forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
Hi F.G A tip for using any 2 or 4 prong drive .File a notch in one of the prongs so that you can replace the wood in the same orientation if you have to remove it to test a fit etc. Theoretically it should not be necessary but in reality it helps maintain the concentricity. Have fun Jako (deep in a pile of architectral turning)
Good tip, Jako. I had to take a piece off a couple of times in class, and I marked a reference on the spur with a felt-tip, and made a mark on the not-yet-finished piece of stock. A notched spur would make it even easier.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
I gotta agree with Jako here. You pretty much need a two prong spur if you're working on green blanks, say roughed out with a chainsaw. The downside to two prong is that it driven into the blank with a fair amount of force and makes a pretty deep dent. Doesn't slip though.
Four prong is good for more square work where you don't want to make deep holes. I haven't used a spur drive, but it seems like it would work even better.
You can always sharpen your cheesey Jet spur with a dremel tool and make it work pretty well. Worked OK for me.
I've not found that a four
I've not found that a four pronged drive center needs a flat surface to engage. An extreme angle will be hard to engage even with a two pronger.
Tom
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