pro-planer issue

[JPG]

I should think before I post: The pulley guard on my stand will not accept a 5" pulley at the motor end, only at the cutterhead (which doesn't make much sense). So I I either need a different pulley guard or I stick with a 3.5 in pulley on the motor. I have pulley guard kits 513552 but these cannot be attached to the planer stand. Attached is a picture of of my guard.

IMG_5826.jpg

Can the guard be mounted upside down?

[GEC]

The current pulley cover is not long enough to accomodate a 5" pulley in either orientation. Seems that my choice is as John suggested buy a new 3.5 inch pulley and remain at 3450 rpm (motor speed) or alternatively decrease the cutter head pulley to a smaller size to increase speed? The pro planer runs at 5750 rpm according to the manual but has a 1.75 hp motor vs the 1.5 hp motor on the stand version of the planer. Could the 1.5 hp motor be asked to reliably run the cutterhead at 5175 rpm (3:2 pulley ratio)?

If I were to use smaller cutterhead pulley would I choose a pulley with a 4L pitch diameter? I am assuming the nominal 3.5 inch motor pulley is 3.5 inch 4L diameter as that is the current belt.

[chapmanruss]

Have you determined what is the maximum size pulley you can use on the motor with your current belt cover? Yours must be an earlier Belt Cover from before they changed the Pulley sizes to get the newer recommended speed of 5750.

If you can go up to 4" on the motor a 2-1/2" on the Cutterhead shaft would get you close to the recommended RPM. If you use your 3-1/2" Pulley on the motor, you could use a 2" or 2-1/4" Pulley to get closer to the desired RPM's. This is if my calculations are correct.

If using a slower RPM, you will need to slow your feed rate accordingly.

[GEC]

I am curious how often the 12" planers spin a pulley and how often cutter head bearings need replacement? I ask because I need to replace a bad pulley on my stand-adapted 12" planer that had two 3.5" pulleys (either zinc die cast or aluminum I cannot tell which). Several have suggested using cast iron pulleys for replacement and shopsmith's now discontinued retro-upgrade kit contained cast iron pulleys. The cast iron pulleys are significantly heavier than the cast pulleys and I cannot find cast iron pulleys that are dynamically balanced. Is there any experience with cast iron pulleys taking a toll on the cutter head bearings? Has anyone encountered cast iron pulleys spinning on the shafts. Is the higher RPMs of the 5:3 ratio pulleys too high for the die-cast pulleys that weigh less and are generally better balanced after manufacturing? All this goes to choosing the right replacement for my pulleys.

Does anyone have educated opinions on whether cast iron pulleys will alter the failure point from the belt/pulleys to the shafts or bearing? In other words am I better off to replace with die cast pulleys that are easier to replace again or are the shafts and bearings sufficient to withstand stresses that the cast iron pulleys might ignore? Any guesses why shopsmith discontinued the 12" planer and pro planers?

[JPG]

In my opinion, cast iron pulleys that are dimensionally stable will cause less wear/tear than a less robust pulley. Based on experience with other devices. Die cast are way too prone to being 'bent' as well as providing less secure set screw threads.

[HopefulSSer]

Any guesses why shopsmith discontinued the 12" planer and pro planers?

Nick has stated publicly that the profit margin was too slim to continue making them

[GEC]

It has been awhile since I was able to get back to the forum. I thought I would update my chosen solution for the planer pulleys:
I took JPG's advice to heart

In my opinion, cast iron pulleys that are dimensionally stable will cause less wear/tear than a less robust pulley.

and bought cast iron pulleys from Grainger. For the motor pulley I bought a 3.45 inch (AX pitch diameter= 3.2 inch) and for the cutter head a 2.75 inch (AX pitch diameter 2.5). The motor pulley was about as large as possible to fit into the pulley cover. The cutter pulley was as small as recommended for use at the expected speeds with a standard cogged AX V-belt. So I compromised on cutter speed. Rather than the 5750 RPM with the pro-planer, this arrangement gives me 4416 RPM at the cutter head - better than the previous arrangement of the stand mounted planer that was 3450 RPM. The motor shaft was keyed but the cutter head shaft had a standard SS reverse taper. So I shaped a key to fit the pulley keyway and the reverse taper and then used Loctite on the key and set screw. I have read alot of posts about the cutter head pulley going off the "rails (i.e. shaft)", including a post showing a pulley welded to the shaft! I now added a regular inspection of the belt and pulley to my maintenance program.

[chapmanruss]

GEC,

Good to hear you found a workable solution.

You said,

The motor shaft was keyed but the cutter head shaft had a standard SS reverse taper. So I shaped a key to fit the pulley keyway and the reverse taper and then used Loctite on the key and set screw.

It sounds like you have an earlier Mark Mount Planer Cutter Head. The picture below shows both a keyed shaft and a reverse tapered shaft on the Cutter Heads. Later ones had both a Keyed side and a Tapered Flat side to the Cutter Head Shaft. No longer a need to have separate Mark Mount Planer and Pro Planer Cutter Heads. I don't believe the extra step of making a key to fit the pulley and reverse tapered flat is necessary. The set screw of the pulley against the reverse tapered flat should hold just the same as attaching a Power Coupler Hub for use as a Mark Mount Planer. The pulley may need a longer set screw to reach the reverse tapered flat than the one originally supplied.

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Planer Cutter Head end labeled.jpg (132.44 KiB) Viewed 13807 times

[GEC]

Russ - The failed pulley was mounted in that fashion with a long set screw through the pulley keyway to the reverse taper and seemed to have slipped and sheared the set screw. That was a Congress pulley, probably zinc so maybe it failed unrelated to the set screw position. Certainly would have preferred the keyed cutter shaft. I considered drilling and tapping a separate hole for a set screw away from the keyway, but I got lazy.