Fabricating a TS arbor: - Specs?

[jon hamer]

Last fall, acquired a "new" 1988 Invicta Delta RT-31 10" scoring panel saw (3hp). This is my first and only real table saw. I got it for next-to-nothing at a liquidation auction, it appeared to have never been run (or fully assembled).

The arbor is short; set up for 20mm bore regular blades only. I intended to use a bushing on the 20mm arbor to run a 1" bored Forrest blade (have it). The saw originally came with an arbor extension - which is missing and no longer available from Delta. I originally wanted to have an arbor extension fabricated, but since I've got it apart - I'm wondering if I should just go for a whole new arbor - a regular 5/8" arbor.
First: Does anyone know if any of the metric table saws have arbor extensions that might fit my 20mm? This would be a simple solution.
If not:
I'm looking for the specific dimensions for a standard 5/8" arbor of sufficient width to run a 29/32" dado stack (or even 1" wide) and still be set up to run regular blades. I am planning to take my arbor specifications to a machine shop, and have it replicated exactly, except for the actual threaded end. What size threads do I go with? Where can I get the blade washer and nut for a 5/8 arrangement? (It's a RIGHT tilting saw.)
What metal should I use? How are arbors hardened/tempered? Is it a good idea to have it magnafluxed or tested for flaws otherwise? I expect that once I get a drawing of exactly what I need, SOMEONE can make what I am looking for, but I've got to know what I want before I go looking.

Thanks for your help
Jon Hamer, New to the 'Creek.

[tyler mckenzie]

i own that same saw, and use 20mm bushing. Mine also came with the 1" arbor adapter, it makes the saw really howl so i don't use it very often.

All i can suggest is taking your arbor out and bring it to a machinist. Modifying or making a new one, i can't tell you which route to take. Maybe try owwm dot com for suggestions.

[jon hamer]

So far, my biggest sticking point is that I don't have any dimensions for a standard 5/8" arbor. Has anyone got any ideas as to where I can find a measured drawing?

Thanks,
Jon Hamer

[Wes Grass]

Off my Dewalt portable:

Arbor is .624 dia, about 1-1/2" long. Thread is a square or Acme profile, about 1" long. Hard to measure the pitch down in there, but it's about 12TPI. The point to this is it gives the threads a flat top to support the blades. A V-thread would be sloppy, as they're typically .005 or so undersize.

The spacer is about 3/4" thick, and about 2-1/2" dia. Washer is 1/4" thick, same dia. Forgot to measure the thickness of the nut.

I'd use pre-hard 4140 for the arbor. Should be hard enough to resist wear, but won't snap off if you hook something hard into the blade. Cutting an Acme thread isn't a huge deal. The nut will be a bigger problem. McMaster only has 8TPI, which would be OK I guess as the grooves are narrower than a typical dado chipper. Might be marginal with a saw blade. The machine shop can make a finer thread nut, and the other pieces as well, but it's probably going to be expensive.

I can check dimensions on a Sawstop at work, but it'll take me a couple days to get over to another building (assuming I remember in the first place). If you can duplicate that, or a Unisaw or whatever, you can probably buy the nut and spacers for a lot cheaper than getting them made. Problem is you have to know exactly what the thread is.

An alternative method is to use a V-thread, but do it as a custom diameter to create the flat top threads. That requires a custom nut as well. If you go that route, have them make a couple extras in case you lose it.

[Chip Lindley]

Jon, there is no such thing as a *Standard* 5/8 arbor. There are many imported clones of, for instance, Unisaw arbors, but don't bet they all match in all dimensions. I sincerely doubt that any other arbor will fit your saw. Since your RT31 is a *specialty* saw, designed for scoring and cutting sheet stock, you will have to have any new, longer arbor fabricated, IMO! A custom milled arbor for your saw will NOT BE CHEAP! Getting a firm quote may cause you to form a Plan B quickly!

IF you do not plan on using the saw for its intended purpose, I am SURE you can make a handsome profit off the sale of the saw, and buy a 10" or 12" saw more suited to general woodworking! Sometimes its easier and wiser to trade up than to modify! For the cost involved, you could sell the RT31, buy what you really want, and live happily ever after!

[Wes Grass]

Sawstop:

Same dia, .624. Arbor is about 1.3" long, and threaded 12TPI square thread about an inch long.

No removable spacer. That limits the thickness of a dado set. And probably done to keep it lined up with the brake shoe. But you'll have some flexibility there.

[Phil Thien]

If you DO decide to have an arbor fabricated, I'd sure love to hear what it costs and how it comes out.

[jon hamer]

Thanks for all of the great replies!

I think my next move is going to be to try to get a hold of an arbor from a 5/8 cabinet saw (Unisaw, for example). Once I have that, I can take all of the measurements needed to fill in the details as to the threads. I want to stay with a thread pattern that I can easily buy a nut for, and will properly support a dado stack.

I know I could sell this saw and buy another that is closer to what I'm looking for. I've decided against this because I suspect the number of production shops interested in an orphaned scoring saw (no parts or service available) is rather low, so I doubt I'd be able to get much for it. In addition, I strongly doubt I'd be able to get "more" saw than I already have with any money from a sale. I admit I've taken a shine to its crisp, front-mounted cast iron controls, too. If I make a 5/8" arbor that can support dado cutting, I'm increasing my pool of potential buyers. I'll also keep the original 20mm arbor for anyone that wants to return it to stock.

Why use a pre-hardened blank? Can't it be hardened after the machining is done or near done?

Thanks!
Jon

[george wilson]

Make sure the thread TIGHTENS the nut in the direction of rotation.

[Wes Grass]

Sure, it can be heat treated afterwards, or before finish machining. And if it needed to be really hard that'd be the only practical way to go. But using pre-hardened material saves the cost of heat treating. Roughly a $75 lot charge around here.

And in the case of 4140, it actually machines better when it's hardened a bit.

[J.R. Rutter]

Short of befriending someone at Delta/Rockwell/Invicta who can dig through files and copy a measured production drawing, duplicating the bearing side from the existing arbor is the best way to go. I would remove the arbor and take it to a machine shop and then you can spec out whatever you want for the blade side dimensions, threads, features, etc.

[John Callahan]

Jon, I'd contact Invicta USA. Invicta still makes the RT-31 afaik; it's still listed on their Brazilian website though not imported into the US. Invicta USA may be able to get what you need. Worth a try ...........

[jon hamer]

Update:
I've talked to a few machine shops - all of which say that they can make an arbor at a price I can live with. My plan is to put a 5/8 spindle onto an otherwise RT-31 arbor. My saw has a max 12” capacity, but with a 12” blade in place, I cannot lower it completely – one inch always stays above the table. The Unisaw arbor I had planned to copy the spindle from has a smaller-diameter flange (2 ½”) where the RT-31 is about 3” across. I want to know if I can still use a 12" blade on this new arbor, or if it won’t be supported well enough dampen vibration. The 12” would not get used often, only for extra-thick material – and I’ve got a bandsaw for that, anyway. The rest of the time, a 10” blade would be used. Dado capacity on the Unisaw (from manual) is 13/16 - I'd like 1". How long should my arbor be for a 1" stack? I am considering a better nut and washer, better than the cereal-box treasures that Delta sent me for top dollar… (the nut is 3/16 thick and the washer is a convex stamping, about 1/16 thick. The washer from the RT-31 weighs about 4oz, it is solid. The nut is also well made- it’s 3/8 thick and has about 6 full (1.5mm pitch) threads inside.
Anyone tried one of these:
http://www.mikestools.com/36-659-Delta-Arbor-Nut-Assembly-Rt-Tilt-Table-Saws.aspx

I’ve uploaded pictures of the arbors and their components.
Thanks,
Jon Hamer

[Wes Grass]

My Felder has a 3" flange, for a 12" blade. It will also accept a 14". I don't see any reason why you can't copy the arbor and keep the 3" flange, unless there's an issue with the dado set.

[Chip Lindley]

3" arbor flange should be fine! Just check that it clears the underside of your table insert when raised to full height. For comparison, Freud blade stiffeners for a 10" saw with 5/8" arbor are 3-1/2" Dia. !

[Bruce Page]

Jon, have you had the arbor fabricated yet? What kind of steel did you decide on? I would not let the machine shop make it out of common cold rolled steel.

[jon hamer]

I think I'll keep the 3" flange and re-use the matching 1" washer by making a bushing to 5/8. Maybe I'll keep with the thin delta nut for wide-dado use, but I'd still like to find a well made nut.

I'm still considering using alloy 4140 for my arbor, but am still open to any other ideas. A 3 1/8" Diameter rod 12" long is about $75 + shipping at Mcmaster-Carr.

Thanks!
Jon Hamer

[Wes Grass]

3" hot rolled heat treated is $57/ft from Speedy Metals. 3-1/4 is quite a bit more, as it's kind of an odd size. They also cut to size and charge by the inch (~$6) which would save you a bunch. Figure how long the arbor needs to be and add an inch for a new washer.

Cutting a slice off the end, boring a 5/8 hole in it and facing it flat isn't going to cost a whole lot more than making a bushing for your existing washer, and it's a much better way to go.

Any shop that can cut an external square/ACME thread can make a nut to fit. Not gonna be 'cheap', but shouldn't be horrendous either. Roughing the 3" stock down on my lathe would probably take me longer than making the nut. I might even consider shrinking the flange onto a smaller shaft, depending on dimensions. Looking at the picture again, that should be no problem. That opens up options in materials, as the flanges can be just about anything the shop has lying around.

S-7 tool steel is a good choice too. Air hardens with little or no distortion, and drawn back to 45RC it's about as tough as anything you'll find. Another is 17-4PH stainless steel, although it has a reputation for galling. Both will require heat treating however, which adds to the cost. And you'd definitely want to go with a shrunk on flange with either as a 3" dia piece will cost a chunk of money both to buy the stock and hog it down.

[Cliff Rohrabacher]

If you use the Felder design you'll have a standard metric.
If the saw has braking you might need anti rotation pins like those Felder uses.

Otherwise just make it whatever bore you want that'll fit your preference in blades.

Any machine shop can make you an arbor.
I suggest you have one made from a good tool steel and have it centerless ground after hardening to get the bearings and blade arbor
O1 would be a fine metal but it rusts fast. D2 and A6 are also fine or you can use almost any of the chisel stock steels (Brine hardening). It would be well to discuss the metal selection with the machine shop guys as they will have some material on hand and you can avoid a special order of steel.

[jon hamer]

Today I got a call from the machine shop (after waiting patiently for two months). My arbor, washer and nut were all ready to pick up. I've got them in my shop now, and after taking pictures to post later, I'm getting under weigh on the installation.

I went with a 3 1/8" flange diameter, a 5/8"x 1 7/16" 12pt LH acme threaded spindle, a custom washer and matching nut (2, actually). The arbor and the washer are made out of 1045, and the nuts are 4140. All are black oxide coated. The dimensions for all were copied from the respective originals, except for the spindle legnth, I added 3/16" there for good measure. The only possible trouble I may run into is that the threads are not 'standard' Delta 12pt ACME threads - they're not interchangable. The nuts fit very well though, and I dont' expect to lose two of them, they're very thick and heavy.

If all goes well, I'll probably have the only 5/8" RT-31 there is!

Thanks to everyone for all of your help!

[Danny Burns]

The nuts fit very well though, and I dont' expect to lose two of them, they're very thick and heavy.

I figure that it would be easier to lose the nut that is not being used, than the one on the machine!:rolleyes:

Glad to hear that everything turned out fine.

[Phil Thien]

I figure that it would be easier to lose the nut that is not being used, than the one on the machine!:rolleyes:

Glad to hear that everything turned out fine.

+1. I'd find a place on the machine and bolt the spare on somehow.

[Rey Barrera]

Today I got a call from the machine shop (after waiting patiently for two months). My arbor, washer and nut were all ready to pick up. I've got them in my shop now, and after taking pictures to post later, I'm getting under weigh on the installation.

I went with a 3 1/8" flange diameter, a 5/8"x 1 7/16" 12pt LH acme threaded spindle, a custom washer and matching nut (2, actually). The arbor and the washer are made out of 1045, and the nuts are 4140. All are black oxide coated. The dimensions for all were copied from the respective originals, except for the spindle legnth, I added 3/16" there for good measure. The only possible trouble I may run into is that the threads are not 'standard' Delta 12pt ACME threads - they're not interchangable. The nuts fit very well though, and I dont' expect to lose two of them, they're very thick and heavy.

If all goes well, I'll probably have the only 5/8" RT-31 there is!

Thanks to everyone for all of your help!

Hi, do you happen to have the specs for what made or is everything here complete? I would like to do the same thing. I just purchased an RT-31 and would like to use my 5/8” arbor sized blades. Any help would be greatly appreciated.

Thank you,
Rey

[Bill Dufour]

Not clear to me. Does this have a screw in saw arbor that seats into a female tapered arbor. Like part 56 on the link. On the delta/crescent 12/14 saw that taper is 30 degrees
Bill D.

http://wiki.vintagemachinery.org/1214ArborBearings.ashx

(http://wiki.vintagemachinery.org/1214ArborBearings.ashx)http://wiki.vintagemachinery.org/1214NewArbor.ashx

[jon hamer]

Not clear to me. Does this have a screw in saw arbor that seats into a female tapered arbor. Like part 56 on the link. On the delta/crescent 12/14 saw that taper is 30 degrees
Bill D.

http://wiki.vintagemachinery.org/1214ArborBearings.ashx

(http://wiki.vintagemachinery.org/1214ArborBearings.ashx)http://wiki.vintagemachinery.org/1214NewArbor.ashx

No Sir, the RT-31 is a one-piece arbor. There was supposedly an extension that could screw on to the end of the arbor and adapt it from the narrow shoulder 20mm to something that could run a dado stack. But I know nothing further about this attachment. I can assure you that it looks nothing like the arbor pictured on that 12/14 Crescent.
Jon

[Alex Zeller]

I think you would be best to just remove it and take it to a machine shop. If you don't know of one another option would be to do a search on ebay. There's several companies that make them for saws like the PM66. I would contact one and see if they would do what you want. Chances are, since they have plenty of experience with making arbors, they can do exactly what you want. Just make sure they actually make arbors and not buy them from someone else.

[jon hamer]

Hi, do you happen to have the specs for what made or is everything here complete? I would like to do the same thing. I just purchased an RT-31 and would like to use my 5/8” arbor sized blades. Any help would be greatly appreciated.

Thank you,
Rey

Hi Rey,
Just by chance, I pulled up this thread from 10 years ago – and I see that you just posted 3 days ago!

I would be happy to assist you however I can. They way that I went about this was to take my existing arbor out, decide what I wanted to change about it, and I brought it to a machine shop and let them measure it. I didn’t have any measuring tools at that time. I see from my comments above that I changed the flange from 3.250” to 3.125” based on material availability, and I made the threaded portion of the arbor a little longer. It is 0.001” under 5/8” to allow for easy blade removal. This worked well. I still have my original arbor, nut, and washer, as well as my custom nut (2), washer and arbor. This setup has worked very well, and I would suggest making a custom arbor to others.

As for materials, it was suggested by others that I use heat-treated or otherwise specialty material for my arbor. The machine shop tested my existing arbor and found that it was not heat treated. I made mine out of 1045 – and it has worked great.
I paid $385 cash for the above. If anyone’s having more arbors like this made, I’d strongly suggest making several of them, as there seems to be interest. I’d buy one as a spare.

For throatplates, I have a ¼” mdf template that I use to buzz around a piece of scrap wood with a flush-cut bit. Works well, and I can have new throatplates whenever needs arise. The factory throatplates are very… open.

Lastly, I’m sure this is obvious to some, but if you run a 12” diameter blade on this saw, 1” is above the table at all times. The saw cuts great, and I like the gear driven front mount handwheels.

Let me know if you have any specific questions. I’ll check back soon.
Jon

[Rey Barrera]

What are the odds of checking this post! Thank you very much. I was wondering how it worked out for you and now that I know it works I’m going to either pursue a machine shop or make it myself on my lathe. Thanks again

[jon hamer]

Hello again.
Just let me know what you need. I've had my saw apart, and I have it, and the removed parts for reference, readily available. I have never operated the scoring part of my saw. I took the 4th V-belt completely off of the saw so that the flat-belt is not powered. I did this because the little scoring blades are (usually) two-blade stacks and are quite expensive. I've found that with a good 10" blade for the purpose, I've never had any trouble with veneered material. This would be different if I was in a production environment. Have you ever tried the scoring arbor? It's always been intriguing- that it can be moved left/right, up/down AND with a 2-blade stack: is also adjustable for the various widths of main saw blades.

Other things about the saw. Because of its intended purpose, the main arbor is further back than "usual" from what I've seen. This hasn't ever bothered me, in fact, it's been helpful for sawing tennons (have cut hundreds), as the jig (a delta) has plenty of "staging area" behind the saw. About that Delta jig: To get it to work "right", I added a piece of 3/4 stock to the clamping face opposite the screw clamp. I also shimmed-out the screw clamp with two stacks of screws under the clamp assembly, as the table slots on this saw are *not placed as they are on other saws (ie Unisaw). I made it work and have had zero trouble.

Dust collection has always worked fairly well, because of the cast-iron shroud surrounding the blade plus the dust port on the back. I wish it was a larger diameter - but it's been pulling about 95% of the dust that otherwise would be flying everywhere. I think if I panned-off the motor-area of the saw, and attached dust collection there, that it'd really help.

I have a Biesemeyer fence/ Delta table extension setup on mine, which I added. Those both had to be modified a little bit, but has also worked well. I think it's a 60" rail on the fence. Only thing weird there was the delta table sections were a bit narrow, so I added a piece of oak between the front and rear rails. Another is that the front rail (with the inch-scale) is a bit long on the left, so that it's sticking out about 6" from the table. I've never done anything about that, but I've definately walked into it a time or two...

I bought a set of original guards, and a pair of original aluminum throat plates a few years ago. The guards are... well. Not my favorites. I've intended to buy an overarm setup since, but haven't. The guard rides on a brace that runs behind the blade, off of the back of the table, and anytime you want to make a stop cut or a tennon, use a sled, you have to unbolt the whole thing.

I've always wanted to make a riving knife arrangement. I think it could be done, to some extent. Let me know if this interests you. I might get to it sooner.

Jon

[Bill Dufour]

The site I linked to the guy made a large diameter flange and welded it onto a smaller diameter arbor. Then he machined it as one piece. The originals are probably forged from one piece to rough size before machining.
The spindle I made for my Delta12/14 saw had a 7/6 hex in the end. That was. a learning experience to make. I should have just made it longer and cut two wrench flats. That is what Delta did later on.
Bill D.

[Rey Barrera]

Hello again.
Just let me know what you need. I've had my saw apart, and I have it, and the removed parts for reference, readily available. I have never operated the scoring part of my saw. I took the 4th V-belt completely off of the saw so that the flat-belt is not powered. I did this because the little scoring blades are (usually) two-blade stacks and are quite expensive. I've found that with a good 10" blade for the purpose, I've never had any trouble with veneered material. This would be different if I was in a production environment. Have you ever tried the scoring arbor? It's always been intriguing- that it can be moved left/right, up/down AND with a 2-blade stack: is also adjustable for the various widths of main saw blades.

Other things about the saw. Because of its intended purpose, the main arbor is further back than "usual" from what I've seen. This hasn't ever bothered me, in fact, it's been helpful for sawing tennons (have cut hundreds), as the jig (a delta) has plenty of "staging area" behind the saw. About that Delta jig: To get it to work "right", I added a piece of 3/4 stock to the clamping face opposite the screw clamp. I also shimmed-out the screw clamp with two stacks of screws under the clamp assembly, as the table slots on this saw are *not placed as they are on other saws (ie Unisaw). I made it work and have had zero trouble.

Dust collection has always worked fairly well, because of the cast-iron shroud surrounding the blade plus the dust port on the back. I wish it was a larger diameter - but it's been pulling about 95% of the dust that otherwise would be flying everywhere. I think if I panned-off the motor-area of the saw, and attached dust collection there, that it'd really help.

I have a Biesemeyer fence/ Delta table extension setup on mine, which I added. Those both had to be modified a little bit, but has also worked well. I think it's a 60" rail on the fence. Only thing weird there was the delta table sections were a bit narrow, so I added a piece of oak between the front and rear rails. Another is that the front rail (with the inch-scale) is a bit long on the left, so that it's sticking out about 6" from the table. I've never done anything about that, but I've definately walked into it a time or two...

I bought a set of original guards, and a pair of original aluminum throat plates a few years ago. The guards are... well. Not my favorites. I've intended to buy an overarm setup since, but haven't. The guard rides on a brace that runs behind the blade, off of the back of the table, and anytime you want to make a stop cut or a tennon, use a sled, you have to unbolt the whole thing.

I've always wanted to make a riving knife arrangement. I think it could be done, to some extent. Let me know if this interests you. I might get to it sooner.

Jon

Thank you Jon,

I will just take the arbor off and follow the protocol you did. I just purchased a used Smithy Mill and Lathe combination machine and am definitely going to make this arbor. I thought I had the adapter for the dado stack on the main blade but it turns out that it is for the scoring blade instead. So I will make the adapter for the dado as well. I have the same set up as you with the fence. What is interesting is that my saw came with two scoring blades but they are single and not stacked. I am learning more and more about this saw all the time. I hooked up a frequency inverter to convert from three phase to single phase 220v and that worked with no issue. The saw works great! I do have the riving knife if you need any photos are specs on that; just let me know.

I'm not sure when I will get to making this arbor and adapter but soon it will happen.

Thank you all the info you've shared Jon, it is appreciated.