Go to eReplacementParts.com and put in Delta Scroll Saw 40-601. They probably have the part and the4y also have a schemematic of the machine that might help. Great people and if they don't have a part, they will find one. Try'em.

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1 430031020002
Yoke
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2 901041500202
Set Screw Obsolete - Not Available
Discontinued
$0.00 N/A
3 430031060001
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5 430034120001

Screw Assy
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7 905010131507

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8 904152231506
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Grommet
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10 430030890001

Blade Support Obsolete - Not Available
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11 901030103318S

Screw
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3 available
$1.44
12 430030270002

Top Blade Clamp
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13 430030790002

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14 905010120303
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15 905010102708

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16 908250131439

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17 430030270003

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18 430030890003
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19 422250680001
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21 901030100760

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$2.70
22 491957-00

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23 901030103318S

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24 438010040080
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25 430030610001
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27 928060231012
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29 901030103318S

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30 430030050002
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31 430020790001
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32 908250131439

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33 430030380001

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34 430030380002
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35 430030790004
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36 901030103318S

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37 430030310001
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38 901030103318S

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39 400061310022

Speed Sensor
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40 901041509428S

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43 901030103318S

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45 901030408015S

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46 904010101614S

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47 430030550001

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48 901030408015S

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49 904010101614S

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50 430020270005S

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51 901041900207S

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52 902020401306

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54 902020401303S

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55 430031080002

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56 901030100224

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57 904010101610S

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58 430030140001

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59 430030540001

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61 426020630001S

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64 430030910001
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65 430020270003

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66 426020950001

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67 491957-00

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68 901030100763

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69 430033900001
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70 901010605770
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71 1087640

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76 904010312925

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77 951010107802S

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78 904010101610S

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79 901030103318S

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80 420011110003

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81 904010312925

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83 438010040075

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101 438020110017

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101 438020070027
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"Go to eReplacementParts.com and put in Delta Scroll Saw 40-601. They probably have the part and the4y also have a schemematic of the machine that might help. Great people and if they don t have a part, they will find one. Try em."

Been there, done that

DeltaMachineryParts, eReplacementPartrs, toolpartsdirect, mikestools, acetool, etc.. all have them either listed as obsolete/not available or "special order".. I contacted Delta and they told me they are no longer available. I also contacted any supplier that had them listed as available but 'special order', and they all told me that they couldn't get it either. E-bay has been a bust as well. Hence my fabrication above!

Cheers,
Brad

 

I think that there are a couple of things that you might try. You could put a meter on the output of the sensor and see what happens when the magnet goes by. It maybe a hall effect transistor. You could then tell if the current magnet is working. If it is, I would just try adding a second magnet and see if the speed is in the proper range.

I did some searching online also and you are correct that it does not seem to be available but there are some good pictures of the sensor and the magnet with the wheel.

 

Brad I just pulled the bottom off my 40-601 and looked at it. There are no magnets showing but I can tell you it is magnetic all the way around it. They are not very strong though. I held a scroll saw blade lightly while rotating it looking for a non magNetic point on the wheel. Might want to try picking up some of those flexible strip magnet from like Michaels and glue it to the edge and see if that may work better. Hope this helps.

 

"Brad I just pulled the bottom off my 40-601 and looked at it. There are no magnets showing but I can tell you it is magnetic all the way around it. [...] Hope this helps."

Thanks a bunch for looking at your machine, however, now I'm totally confused !!!

The sensor obviously picks up some kind of magnetic signal from the rotor, as otherwise my 'fix' wouldn't be working at all.. a continuous magnetic field doesn't seem like it would offer any input at all to the sensor! Maybe they are just spaced so close to each other that it appears to be continuous.. I dunno. I think my next move is to try and find a way to measure the speed it currently runs at (at the slowest setting) and compare that to what it 'thinks' it's running at via the front indicator (40 SPM). If I can get a ratio (actual vs indicated) then I might be able to figure out how many more magnets it needs. I was hoping this would be a bit easier to figure out!

Cheers,
Brad

 

If it's a hall effect sensor, I think all you need is a chunk of metal. You need to know how many lobes the original had on it. If the original had 4 lobes, and you are trying to use 1, it will run 4 times as fast. Look up how a ignition coil pickup on an 1970's vehicle works, or even the crank and camshaft sensors on modern vehicles. It's just a chunk of metal with teeth which induces a very small voltage into the winding.

 

I was looking at the picture and there is no indication how many pieces of metal are in the thing.

http://www.mikestools.com/430-03-100-0001-Delta-Speed-Control-Rotor.aspx

This picture on Ebay shows 4 casting marks in the palstic. But I think that's probably from the mold.

http://www.ebay.com/itm/Speed-Sensor-Rotor-430-03-100-0001-for-Delta-40-601-18-034-Scroll-Saw-/261447031797?nma=true&si=rtX0%252FPwCcl1Ej7FbFyazAGN57TI%253D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557

 

sounds like I might help. I had two 601's sold 1 to a guy from work , 3 weeks later his rotor shattered
Took mine off,thinking I could turn one out on lathe .
To count magnets I used one of those hard to reach expandable magnet tools , stuck it on vise held the rotor close ,
Counted 28 pauses . Not very strong mags but easy to count
Thinking I will try hole punching some those flat icebox mags ,not sure how to apply to new rotor

 

Counted 28 pauses . Not very strong mags but easy to count
Thinking I will try hole punching some those flat icebox mags ,not sure how to apply to new rotor

Wow..

I know mine is running fast with just 1 magnet.. but I can't imagine that it's running 28x fiaster! Even so, it is functional as is and I've been giving it a pretty good workout lately. First scroll saw I've ever owned and I am having a lot of fun with the thing.

Thanks a zillion for taking the time to check it out. We all finally know the answer to 'how many magnets' I also like your idea of the fridge magnets and may give that a try to see how it goes. I'm thinking that they could be attached (glued) to the outside edge of the rotor then the whole thing covered with a couple layers of polyurethane or even painted over to help keep them in place. Maybe get fancy and fill in the gaps between magnets with some epoxy or something. Sure would be easier if I had a lathe!

Cheers,
Brad

 

Just an update on this..

A few months ago I picked up a nice little Delta lathe (~1948 model 46-110) that I finished restoring a couple weeks ago. Came out really nice and works great, so I decided to try fabricating a better speed rotor for the scroll saw with it.. I wanted to try the refrigerator magnet idea to see if they were strong enough for the sensor to detect. I grabbed the strongest magnet I had on the fridge, which still is pretty weak as far as magnets are concerned. Then I punched them out using a standard hole punch. The punch produces a circle just a gnats hair smaller than 1/4 inch, and a 1/4 inch forstner bit was used to drill the slightly recessed holes for them to sit in. I glued them in and then coated the whole outside edge with a couple coats of polyurethane to keep everything in place.

Unfortunately, it didn't work. It acted just like it did when I first got it (without a speed rotor), with the speed all over the place varying from fast to slow and back. It seems those magnets just don't have enough strength apparently. Next step is to try and find some stronger magnets. Updates to follow when I do.

Cheers,
Brad

 

You might try adjusting air gap to .010. This info I found on vintagemachinery.org website under the publications reprint section scroll saws dated insert 03-10-2005. The rotor p/n 125 would have had metal spaced around it "teeth" that the sensor would "count" and send pulses generated by the "hall effect" pick-up sensor p/n/39 to the controller. Also found that this rotor was used on lathes 46-400 type1 & 2. The metal teeth are just that- metal and not magnets.
Hope that this helps.

 

Thanks Bob.. I have that service buliten and did set the sensor gap to 0.010" or better. Also, there appears to be some disagreement about what is actually in the rotor. You can't really tell by looking at an original one as they just look like a plain plastic disc with a metal hub. Some (like you) say it's just metal, others say it's magnets. My original attempt at making a replacement rotor used a single magnet, and it did actually work to regulate the speed.

If it is a Hall effect sensor, like I and most others believe it is, then the rotor should have magnets in it. Hall effect sensors vary the output voltage in response to a magnetic field, which kind of supports the magnet theory. However, I made a custom faceplate for the lathe to make it easier to make the rotors, so I can fab up a small batch of them and test various configurations.. magnets, different types of metal, number of them around the rotor, etc..

Cheers,
Brad

 

All the hall effect sensors I have seen use a ferrous metal rotor. Go look at the anti lock brakes on your car, or the cam or crankshaft sensor, or a distributor made between the 70's and 90's.

 

Not to get off topic, but there are two major system types of non-contact speed detection of a rotating shaft (well, three if you include optical); inductive and active. For inductive, the magnetic field is inside the sensor and it measures the field change as a frerromagnetic rotors teeth are passed by it. Active sensors use a Hall effect transistor to vary it's output voltage as an external magnetic field passes by it. What type is used on these scroll saws is currently unknown, but I do know that it worked when I used a magnet, which leads me to believe that it's a hall effect sensor, not an inductinve one.. but I will test both to be sure.

Cheers,
Brad

 

I see. My father sells inductive type ones for manufacturing (robot) uses. Quite amazing, but simple at the same time.

 

Update.. SUCCESS!

I ordered a batch of 100 1/4" rare earth magnets from Amazon to try out in the rotor (really cheap.. just under $7 and free shipping). Apparently though, these things literally came over on a slow boat from China.. I ordered them online on October 20th and just got them yesterday (November 17th).. and the labels on the envelope (in both english and chinese) were marked "China Post"! Heck, I don't care.. they were cheap and I wasn't in any real hurry.

So I made up a rotor to test, installed the magnets and threw it in.. and it worked great. It's a completely different machine now and runs like new. So for anyone with one of these saws with a busted rotor, there is hope! Even though the stock rotors are no longer available, one can be made fairly easily for a couple of bucks. Thanks to everyone who helped me solve this problem! It would have been a big green paper weight without the assistance.

Cheers,
Brad

PS: As an added bonus, using the much stronger rare earth magnets makes the air gap setting between the sensor and rotor completely non-critical. I forgot to adjust the sensor when I tested the new rotor, and there was about a 1/8" or larger gap.. still worked great and moving the sensor closer had absolutely no effect on how it ran. Kind of makes sense, as rare earth magnets were very, very expensive back when these machines were made, so they most likely used much weaker ceramic magnets which required closer placement.

 

Mr. Unix, I purchased this scroll saw in 1988 and enjoyed it until a few years ago when the speed started varying uncontrollably. I left it alone until last week, when I disassembled it and discovered the Speed Sensor Rotor in pieces. I then started the web search for replacement parts and discovered your post. I am going to try your repair as the rest of the saw is in excellent condition. I am going to order the "slow boat from China" magnets but I am unsure what glue to use. What did you use to glue the magnets and how did you attach the the replacement rotor to the existing shaft? I would appreciate any info. and suggestions.

 

You can probably use any glue you like.. I just used regular wood glue (titebond). I drilled 1/4" holes about 1/16" deep with a forstner bit just like shown in my post up towards the top of this thread. Once they were glued in, I made sure they would not come out by coating the outer edge with a couple coats of polyurethane which sort of sealed everything in place. Initially when testing, I just wrapped the outer edge with some electrical tape and that worked just fine as well. One tip that might be useful: I found that the interaction between magnets made them want to flip and pop out occasionally when trying to put another one next to it.. so I cut down some stick pins from my wifes sewing box and stuck them in each hole with the head slightly sunk into the wood.. this gave the magnets something to stick to while I was installing them.

As for securing to the shaft, you can re-use the metal hub from the original rotor like I did with my first prototype (with one magnet). What I eventually wound up doing was to make a wooden faceplate for my lathe with a 3/8" bolt centered on it. I drilled a 3/8" hole in a wood blank, mounted it on the faceplate and then turned it on that.. which ensured that the rotor was perfectly centered around the shaft. I started out with about a 1" thick piece of stock and made an extended hub that I could then drill and tap for a set screw (#8-32) that I made from a spare screw (just cut the head off and use dremel to make a screwdriver slot):

After drilling and taping, I sanded the hub down so the whole thing was just a bit shy of 3/4" thick, which is about as wide as you can go without running into clearance problems. It fits pretty snug on the shaft anyway, and with the set screw lightly tightened against the flat spot on the shaft, it ain't going anywhere.

Cheers,
Brad

 

Brad,

Thanks for the quick reply. I will give this a try and let you know how it works out.

Jeff

 

Brad,

First off THANK YOU!

Just curious how many magnets you ened up putting on the final rotor?

You should whip up a few more rotors with the extra magnets and sell them.

 

Thanks Jeb (and Jeff!),

The rotor really needs 28 magnets, but because I bought 1/4" ones, there is no way to fit that many on a 2" diameter rotor (you can maybe get 24 or thereabouts if you place them really, really close to each other). Since my lathe has 60 indexing holes, I just went with 20 to make things easier. It still works just fine, although it does run slightly faster than what the front indicator says it is.. which I haven't found to be a problem at all so far. The slowest speed it can be set to is 40 spm which is way, way to slow for anything I can think of doing, and with the 20 magnet rotor, it is still way too slow for any useful work (probably closer 60 spm with the replacement rotor). And the upper end of the speed range is well beyond anything I would want to use, so even with the replacement rotor, there is a nice wide speed range available.

I've thought about ordering some 1/8" magnets and trying to make some with 28, but since the one I have works so well, I'm not all that motivated and would rather just cut wood As for making extras and selling them, I'm not sure there is much of a demand.. but if enough people express an interest, it wouldn't be too much trouble to crank out a few extras.

Cheers,
Brad

 

Brad, are you still hanging around this forum?

 

This thread gave me a little inspiration to tackle the broken rotor on my scroll saw. I used the original hub from the rotor and 1/2" plywood. I used 24 magnets because that's what came in the package I bought. I'm not really concerned with the accuracy of the readout, so long as the speed is stable. I put the magnets on edge to allow more magnets. I coated the assembly with epoxy to secure it all together.

 

I like the idea of placing them on edge like that.. did it work? Just curious because the magnetic field radiates off the faces of the magnets, not the edges (which is why I placed mine flat). Orienting them like that would solve my space problem, and I could make up a rotor with the correct number of magnets (if and when I get the motivation to mess with it more)!

Cheers,
Brad

 

So far it seems to be working good. There's a bit of vibration I still need to address. I'm not sure if my modification is causing it or if it's something else. I bought the saw broken for $45. Even with the vibration, I think it was worth it. If I discover the cause, I'll post it here.

 

I'm pretty sure my counterbalances are not aligned correctly. I didn't consider marking them before I pulled the assembly apart to replace the rotor. Is there an indexing mark or some other approach to getting these lined up correctly?