Vintage Delta Start Capacitor Problems.

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My vintage 1HP Delta Drill Press was working normally until last week it will not rotate but hums when I turned on the switch on. I removed the motor from the DP and powered up. It still will not rotate but starts to hum again. I rotate the pulley manually, it begins to rotate and speed up normally and the humming stop. I switch off the motor, before it stops completely I switch the motor on and it speeds up normally. I did another test: I turn the switch on, as it starts humming, than I rotate opposite direction, it speeds up and again it stops humming. Can I assume the start capacitor is bad? If, so where can, I buy a replacement. The Capacitor is an old one; Manufacture Name": SF??? MIKE" Type H, 210 259 MFD. 115VAC"
Thanks for your help.
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Check the yellow pages for any motor repair shop in your area. You need to match the MFD and voltage ratings of the capacitor for performance reasons and the physical size for obvious reasons, so I'd advise taking the old cap with you when you go. Note that the voltage rating on the replacement can be higher than the original, but should not be lower.
You could also do a Google search for online sources:
If the link below is inoperative, do a search on (without the quotes) "motor start capacitor" and click on the "shopping" link.
http://www.google.com/products?hl=en&as_q=start+capacitor+motor&as_epq=&as_oq=&as_eq=&num &lr=&as_filetype=&ft=i&as_sitesearch=&as_qdr=all&as_rights=&as_occt=any&cr=&as_nlo=&as_nhi=&safe=images&oe=UTF-8&um=1&ie=UTF-8&sa=N&tab=wf&oi=property_suggestions&resnum=0&ct=property-revision&cd=1
Here's one that seems to be compatible with the electrical characteristics of your old capacitor, don't know about the physical size.
http://www.drillspot.com/products/59585/Cge_61B7D220216NCGR_Motor_Start_Capacitor
Tom Veatch Wichita, KS USA
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On Sun, 21 Sep 2008 23:23:43 -0500, Tom Veatch wrote:

Hi fellow Kansan, I brought this DP from KC to the Bay area in 06'. I did a search in the Internet and could not find an exact specification as marked on the old capacitor. Yellow page here in the SF Bay areas are practically useless that is why I posted here looking for help. The above link still does not give me the detail I need to buy the "exact or acceptable" capacitor. I hate to burn up the motor since I took so much effort to moved it two thousand miles away.
Thanks

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Go to http://www.mcmaster.com /
Left side of the page, enter "capacitor" in the search box
Third one down in the "AC Motor Start Capacitors", "110-125 VAC Capicitors" is part number 7245K112.
The electrical characteristics are correct for use as a replacement for your old capacitor, "Type H, 210 259 MFD. 115VAC". Whether the physical dimensions are correct is another question. If it will fit within the "bump" on the motor, go for it.
I've ordered from McMaster-Carr many times. As I recall, the "Company Name" field is not a required field, so if you don't want to make up a company name, just do as I do and leave it blank. They aren't like Grainger which does require a business name.
Tom Veatch Wichita, KS USA
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Take it from an electric motor repairman - disconnect the capacitor and short the two wires together. If the capacitor is bad, the motor will start (it may start slowly, but it will start). If the motor still won't start, the problem is with the starting switch inside the motor.
If the capacitor is bad, you can replace it with anything near the same mfd value. A general ballpark for a 115 volt motor is 400 mfd per horsepower, so a 1/4 hp motor would be 100 mfd. For a 1/2 hp motor the value would be 200 mfd. If you get too far away from the original value, you will lose starting torque in the motor, but for a drill press, that's not usually significant.

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Did exactly what you suggested. Yes, it start. I knew it was the capacitor, cuz the switch was solid and sound. Thanks.

The motor is 1HP (original Delta), Type H 216 - 259 MFD 115 VAC. From McMaster (Carr page 925) :
PN# 7245K114 AC Motor-Start Capacitor 340-552 Rating, 1-7/16" Case Diameter, 110-125 VAC PN# 7245K112 AC Motor-Start Capacitor 216-389 Rating, 1-7/16" Case Diameter, 110-125 VAC
Look like PN# 7245K112 closest to my original capacity, what say you?
Thanks again.

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If you click on (maybe double-click) the part number in the catalog listing, the data for that part number will appear in the pane on the left side of the browser screen. In that data will be a drop down box that allows selection of a specific capacity range. As I recall, one of the selections is the exact capacity you originally reported. When you select it, the capacitor part number will change to the one for that capacity.
Tom Veatch Wichita, KS USA
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On Wed, 24 Sep 2008 00:20:18 -0500, Tom Veatch wrote:
Yes, I double click the PN and it show the capacitor spec. I believe that's the one I should buy.
I did not go to the trouble of disassemble the motor as suggest by some woodworks here to find if the switch is the problem. Anyway the switch is mounted externally. I just tested the capacitor by shorting it as suggested by Doug. Thank you and everyone.

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You should use as close to the original value as possible for the best starting torque. Must be your motor is 3450 rpm. My original reply about motor capacitors was based on a 1725 rpm motor. For a 3450 rpm motor, the capacitors are usually around 200 mfd per horsepower, so that would fit with what you have. Like I said before, you don't have to be exact on the mfd value. Even brand new start capacitors usually have a 10 percent tolerance. If you put one in that has a large difference in mfd value, stick a piece of masking tape on the new capacitor and write the original mfd value on it in case you have to replace it again at some point.

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I ordered the capacitor from McMaster-Carr this morning: PN# 7245K112 AC Motor-Start Capacitor 216-259 Rating, 1-7/16" Case Diameter, 110-125 VAC. It's exactly the same spec. but 1/16" larger in Diameter and the capacitor casing is slightly larger anyway.
Thanks Doug, I really appreciate it.

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Yes.
You need to buy a replacement start capacitor of similar capacity. A few bucks plus shipping. They are plentiful, see McMaster catalog page 925, for example. Item 7245K17 should work.
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On Mon, 22 Sep 2008 00:06:25 -0500, Ignoramus6193

Thanks for your confirmation. Before I removed the motor from the DP I suspect either, the bearing or carbon brush was bad. As I rotated the pulley it rotated freely. I knew immediately it was the motor's start capacitor. I wish I had tested my lightly used, new 8" jointer's motor in KC before I moved. It had the same symptom. I sold the jointer for a song, and the buyer insisted I gave him the old motor as the new motor (I kept the new Baldor motor). I bought with the incorrect RPM. Thinking back, the buyer must be thinking how stupid I was.

I should have thought of McMaster before I posted here. However, I would like to know how do you buy from McMaster? They need company names etc, and I am buying for myself? I went to page 925 in McMaster, but no part 7245K17.
Thanks for your help, any other source with a correct capacitor?
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WD wrote: ...

In a place as large as the Bay area, there are bound to be a zillion local motor repair shops that can supply your needs...
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Just make something up. Or you can do what I did and put in what I will call my company if I ever decide to start one. I've bought from them a number of times and they've shipped straight to my house, no problems.
The only thing I don't like about their setup is that they don't tell you shipping up front, so you have to check the invoice. It's very reasonable, though. They're not the kind of company that will charge you $10 to ship a $2, if it doesn't actually cost $10 to ship it.
-Nathan
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I have a corporation, so I did not have to make anything up, but I would go the above suggested route. Their shipping is very much on the low side.
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"WD" wrote:

Two (2) possibilities.
1) Bad start capacitor.
2) Bad centrifugal switch.
Grainger can do a match up for a replacement capacitor.
Replace cap, if that doesn't solve problem, head to a motor repair shop.
Replacing a switch is a total PITA.
My guess is you will spend 60%-70% of new motor cost to make repairs with makes which makes repair a tough call.
YMMV
Lew
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Thanks Lew, we have already established it is the start capacitor that is bad. I will attempt to buy it from McMaster-Carr. Thanks again

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And how did you determine this?
More often than not it is the centrifigual switch. May have dust in the contacts. Supposed to be a rubber boot that makes it dust proof, but, depending on the origin of the motor, maybe bad.
Does what you describe. Does not let the start circuit pull in. Contacts are supposed to close when the RPM's run down, but dust prohibits. When you spin it your are doing the same thing as the start circuit does, that is, starting the motor.
Frank
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On Tue, 23 Sep 2008 07:56:18 -0500, Frank Boettcher

I've not witnessed a large majority of all motor failures of this type, so I'm not qualified to dispute that statement. But I can say that I have experienced two motor failures that presented the reported symptoms. In both cases, the failure was due to a leaking and failed capacitor. The switch in both cases was defect free. But, perhaps my experience is atypical.
Tom Veatch Wichita, KS USA
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On 2008-09-23, Tom Veatch <Tom> wrote:

I had the same experience.
To test for centrifugal switch, disconnect starting capacitor and measure voltage on capacitor leads during startup. (briefly, so as to not smoke the motor). No voltage means bad centrifugal switch.
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