Reprex No. 2 Missing drive gear

Reprex01I recently acquired a Reprex No. 2 [No. 1] proof press.  While everything on this Reprex appears to be in excellent shape, it is in fact missing the drive gear on it’s form roller. The original manual I have specifies that there should only be one drive gear, and the part number for this gear is D48 on the Reprex parts list.

Reprex02Assuming I won’t be able to locate a replacement part off another press, it looks like I’ll need to have one made. I need to determine proper specs for the gear, since the gear rack and roller cores differ from those on the Vandercooks I have access to. Unlike many of the Vandercooks I’ve seen, the gear rack for the inking system on the Reprex appears to have the same tooth pattern as the gear racks for the entire carriage. What I know at this point is that the diameter or my roller cores are 0.5″ and the roller diameters are 2.5″. There’s an image below of the gear rack for the missing drive gear for measurement purposes.

Reprex03I’m hoping some other Reprex owners may be able to offer some insight on replacing this drive gear in whatever way possible. I’m thinking I should be able to have a new gear machined if I can supply a gear diameter and correct number of teeth to correlate with the gear rack on the press. Or perhaps the gear/rack is a standardized part that may be readily available?

I’d greatly appreciate any and all info anyone may be able to share. I need to (hopefully!) get this press up and running for a visiting artist by mid-March, so I’m trying to tackle it as soon as possible.

Many thanks!

14 thoughts on “Reprex No. 2 Missing drive gear

  1. Josh Dannin - April 5, 2014

    Hi all, just a quick update — I was successfully able to have a stock gear modified for my Reprex. I started out with Boston Gear NH20B (thanks for the lead kpmartin) and a local machine shop was kind enough to do some complimentary work on it for me. They milled down the gear face width, the hub width and OD, installed a bore sleeve, and tapped it with two set screws. All in all a beautiful job, and the gear works great. They’ll certainly be receiving a few prints in the mail.

    Thanks again for all the input!

  2. Josh Dannin - February 26, 2014

    Thanks kpmartin, I was able to gain a bit more specific information regarding the specific gear for my Reprex No. 1 (now confirmed – sorry for the mix up!). Pictures and specs are below, with the huge help of Sue from Cranky Press in Ottawa who was kind enough to assist me with a ton of measurements and photographs.

    I’ve since been in touch with quite a few different gear manufacturers, including Boston Gear and Rush Gears. Boston told me that what I was working with certainly wasn’t a standard item, specifically citing the thin gear face width and the small bore diameter. Rush Gears, who are able to customize gears, took all the information and pictures and got back to me with the following:

    It appears to be a special “elongated” tooth form. We would need a Sample Gear in order to Reverse Engineer it properly. Our typical setup charge for this type of Gear is $1800.00 with a Standard Production Time of 3 Weeks.

    That’s not something I’m exactly able to take on at this point, and it also confirmed that this is a specialized gear. So I’m exploring other options. In any case, the measurements I’ve figured out are below. I’m going to finalize the pressure angle this weekend by measuring the gear rack.

    Diametric Pitch: 8
    Pressure Angle: either 14.5 or 20 (will confirm this weekend)
    Number of teeth: 20
    Backlash: _______
    Outside Diameter: I was provided with the measurement of 2.875″, however I’ve also been lead to believe the diameter should be 2.75″, based on the dicussion here on the Vanderblog. However, the 2.875″ diameter measurement is based on the gear in the attached pictures.
    Pitch Diameter: _______
    Face Width: 0.45″
    Bore Diameter: 0.5″ — Based on the 0.5″ roller core
    Hub Diameter: _______
    Hub Length: 0.45″
    Gear Rack Width: 0.5″

    Any recommendations for alternative (less expensive) gear fabricating options would be greatly appreciated. Thanks again!

  3. kpmartin - February 25, 2014

    Gear diameters are measured at the pitch diameter, which is about halfway down the teeth, not the tip-to-tip diameter. The pitch diameter should equal the form roller diameter (otherwise slurring will occur). For 2.5″ rollers you would want a 20-tooth gear. Although a pressure angle of 14.5 degrees is most likely the place to measure this is on the rack, not the gear. The pressure angle is half of the vee angle formed by the teeth on the rack (and also the gaps between the teeth).

  4. Paul Moxon, Moderator - February 6, 2014

    There are seven known No.1 in the Reprex census. I will ask these owners to provide the specs.

  5. Josh Dannin - February 6, 2014

    Many thanks for all the information guys, I really appreciate your assistance. I’m now suspicious as to whether or not this press is actually a No. 2, or if instead it’s a No. 1 with power ink distribution.

    Based on the Reprex product sheet photos I looked at here on the Vanderblog and images of other No. 2 presses I had found online, it looked like it was a No. 2 – specifically the pedal design, which matches that of the No. 2 catalog but not the No. 1. Also my press has the rear trip lever, which the No. 1 doesn’t appear to have, though I may be wrong. That said, the cabinet design doesn’t match that in the No. 2 catalog photo. I attached two photos of my press — We can’t seem to find a model listed anywhere on this thing.

    My press bed measures 15 1/4″ across, and the inside edge of the dead bar to the inside edge of the holes for the press pins measures just about 26 3/8″.

    It seems like my 2.5″ diameter rollers are designed for this press, based on how they fit nicely with the ink drum. Assuming this is the case, I’m wondering if it’s possible to determine if the gear specs that Mike Day and Maysorum listed could be scaled down to the appropriate gear for my press. It looks like I’ll need one that’s 2.75 in diameter, but is it possible to determine the correct number of teeth based on this diameter?

    Mike Day and Maysorum, do the gear racks on your No. 2 presses appear to have the same specs as the image I initially posted?

    Thanks again for your help. I apologize for the possible press confusion and my mechanical ignorance – I don’t have a ton of experience with this type of gear work.

  6. Paul Moxon, Moderator - February 5, 2014

    Mike, as to model, I was going by what’s in the Reprex census. Perhaps I incorrectly recorded the info provided to me. This would be going back several years now. Given that the bed is only only 15″ wide that would indeed make it a No.2 and not a No.3.

  7. Mike Day - February 5, 2014

    Is it possible that Josh’s rollers are the wrong size. I am reasonably sure our Reprex is a no. 2, not a 3. I don’t have the spec sheets handy to check. Any way, if it is 2.5, the gear would be .25 larger or 2.75. The half inch core is consistent. The bed is 15″ wide allowing for a 141/2 form. Certainly not 19″ wide. All I can say is it prints well when adjusted.

    I believe we had our roller made by NA Graphics and probably sent the cores and old rollers to them to match.

  8. maysorum - February 5, 2014

    My Reprex no. 2 has the same drive gear dimensions (3.25in) and number of teeth (24) as Mike Day’s press. The rubber rollers are 3in in diameter as well. Hope that is helpful.

  9. Paul Moxon, Moderator - February 4, 2014

    Reprex product sheets do not state roller specs but note that the maximum form for a No.2 is 14½ × 22½” and for a No.3 is 19 × 26″. So a 2½” diameter for the No.2 and 3″ diameter for the No.3. is comparable to a Vandercook SP15 and an SP20.

  10. kpmartin - February 4, 2014

    Mike, your rollers don’t seem to be the same size as the ones Josh mentioned; he says his as 2.5″ diameter but yours look like they are 3″.
    Your gear has the same diametrical pitch of 8 teeth per inch of diameter, though.
    Perhaps the roller height adjustment on this press has enough travel to accommodate either roller diameter?

  11. Mike Day - February 3, 2014

    One more photo. Paul, could you reduce the size of the first. don’t know why it is bigger. all were same size.

  12. Mike Day - February 3, 2014

    I am attaching three photos. I hope this is what you are calling the drive gear. The diameter is 3.25″, gear tip to gear tip. The teeth are 7/16″ tall. 24 teeth. Inside diameter of base of gears 2.8125. The hub diameter is 1.375″, forgot to measure its length. shaft for roller and hole in Hub is .625″.

    The hub is locked on the shaft by two hex allen head screws .1875 diameter. The two holes are 1 quarter apart on the hub. The roller has about .125″ play side to side so the gear needs to be positioned so it does not get off the track. We had to cut some of the rubber off when we had them recovered to make a flat end for the gear. Inside (roller side) of gear is flat whiled outside is convex.

  13. kpmartin - February 1, 2014

    That seems to be 18 teeth in 7″ linear rack, which represents a diametrical pitch of 8 (that is, a gear that matches the rack will have 8 teeth for every inch of diameter). You want a gear whose pitch diameter is 2.5″ (to match the roller) so you need a 20-tooth gear with a 1/2″ bore. There are two common pressure angles (equal to the incline of the tooth face on a rack), 14.5 and 20 degrees, but I can’t see the teeth in the photo to tell (it is almost assuredly 14.5 degree). Boston Gear NH20B-1 looks like the right teeth but has a 1″ bore and would need a bushing for the hub so it would fit the 1/2″ shaft. Boston Gear GH20 has a larger bore but might be cheaper. Either way a hub has to be made. Both of these are 14.5 degree pressure angle.

    This is of course all on the assumption that this is standard gearing, but that’s a pretty good assumption.

    I did something similar for an SP15 that had an oddball roller diameter and adapting a 38-tooth gear to replace the standard 40-tooth one was cheaper than re-covering the roller (but then I made the hub myself and so did not have to pay a machinist).

  14. Mike Day - January 30, 2014

    I will take a photo or two of the gear on our press and post the measurements in a day or two. I am not at the college right now.

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