Covel 7a surface grinder help
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  1. #1
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    Default Covel 7a surface grinder help

    I recently purchased a covel 7a grinder. It was in great shape. I was super impressed. I stored it at my work as theres extra space until I could clear some space in my garage.

    Came to do the final move and its obvious someone knocked over my machine. Therrs a dent in the electric box on back and most importantly, I assume the table got flipped off as the 2 rollers along the x axis ways are missing.

    I'm assuming that i am $#*t out of luck and my machine went from me being super excited about having my first grinder to now a 1000 lb paper weight.

    Just looking to confirm theres nothing i can do.

    Thanks for any help.

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    I can certainly appreciate how you feel but I would suggest that you donít do anything too drastic yet.
    If the 2 missing rollers were side by side in the track near the end you could try taking one from farther along the track and putting it in place of one of the missing ones and then try using the machine .
    I have a small slide with a couple of missing rollers and while it isnít ideal to have missing rollers it may not affect the ability of the machine to do decent work without them .
    You may be able to buy a new set of rollers from a bearing supplier that will be the same size as the ones on your machine.
    If they are worn at all it would be best to do with out the two missing rollers or buy a complete new set.
    Perhaps if you post some pictures of what your rollers look like someone will be able to offer some more suggestions .
    I think someone posted on this forum about a supplier for track rollers for a Brown and Sharpe grinder not so long ago.

    If you plan to move the grinder you should lift the table and remove the rollers and either transport the table separately or put wooden strips in place of the rollers and the guide cages and strap the table in its place on the cross table so it canít move until it is in its final location and then re-install the rollers.
    That way if the machine gets dropped or goes over a big bump on the road the rollers wonít make indentations in the tracks or get flattened from a heavy impact.
    Over 30 years ago the new cutter grinder I got from Europe was shipped that way without the rollers installed and I had to put them in when the machine was in its place.
    Regards,
    Jim

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    Thanks for the reply Jim. For some reason I can't post pictures on my phone. I will get on the computer first thing tomorrow and post them.

    The problem is I'm missing both tracks of the rollers. There was one flat and one vee that both had the rollers in it and I'm assuming whoever knocked my machine over didn't care to or know to put the tracks back on my machine and now they are lost.

    I have a company online, Dunbar rollers that manufacture exactly what I need but its $600. I guess it's a matter of money now.

    I also read that these grinders were also ran without the roller tracks. Not sure if mine can do that. The blocks that hold the belt under the table are just a shade too high and hit the bottom of the table now that the rollers are gone and it sits lower. Not sure if theres a way to fix that. Again I'll post pics in a.m.

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    likely it is worth the $600 for replacement roller racks,
    likely you could make the racks easy enough...but new bought ones better..who knows about used ones. Mostly roller or ball way machines are not cleaned and the back set gets a beating. It is so easy to pull most roller/ball tables so a shame they don't get cleaned. Very easy rollers to make with having centers at the pin hole and run on a grinder or a good lathe. likely the originals were hard but who knows.

    A good service would be to go around to pull and clean ball and roller machines..Yes, and put a strip of masking tape along the parting line between the long travel and the base or saddle at the back side..what a shame guys don't do that. Another service might to go around with a proper wheel and grind chucks.
    Scraped oil way machines tend to self clean because the oil can push out some of the grist that would like to soak into the works.

    I like to soak a broken bolt/screw for a week with WD or better..Dremel a small center nick with using my lope to make/see it very near center..then small drill a hole all the way through the broken screw .. then use a easy-out to screw it out..seems to always work.

    *Perhaps a PM guy can tell what size the rollers..if front and back are the same size..look like 3/8 to 1/2"

    Here a rebuild of a similar machine showing a roller rack.
    YouTube

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    Perhaps the quick fix and as good as used rollers might be drill rod drilled with a clearance hole and perhaps using 1/4 screws for the pin..

    Agree mild drill rod would not be as long lasting as hard rollers but would last a good long time.

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    Here are some photos. I am wondering if I mill the bottom of the table where only a small 2x4 section is hitting the belt tensioning block and ran it with no rollers. Iím guessing that would be better than sitting useless for a year until I can spend 600 on new rollers.

    Any thoughts
    Attached Thumbnails Attached Thumbnails a1633b73-f851-4854-b38b-f45690196e65.jpg   2d027af6-001c-45b8-8c2e-c08c93347964.jpg  

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    Robby,
    The roller slides on machines I have are made differently and I was thinking that you were only missing a couple of rollers .
    Mine have a brass or plastic strip with slots that the rollers drop into .
    They are more like the rollers found in a straight roller bearing with out any reduced ends to fit in the strips .
    Cincinnati cutter grinders use large ball bearing balls .
    before you mill anything off your table I would suggest you contact Abom 79 of the Youtube video in Michigan BuckĒs link who also posts on this forum under the same name and see what he would suggest if he doesnít happen to see your thread.
    If you search this forum for Abom79 you can send him a private message or an email buy clicking on his name.
    I tried a couple of searches for Roller Bearing ways but didnít turn up an image that I was hoping for.
    I have attached a picture of some small used Ina rollers with plastic cages that I kept for an example when I replaced them with new ones on one of my smaller machines that were not that expensive.
    They were getting rough when I replaced them but the ways were still Ok
    You might try and see if a bearing distributor can supply something similar in the size range you need for much less than $ 600.00 .
    I donít have a picture handy of the ways on my larger machines handy to post.
    Regards,
    Jim
    Attached Thumbnails Attached Thumbnails dscf8854.jpg  

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    ntn-needle-roller-bearings-ff3525-linear-flat.jpg_350x350.jpg
    imgurl:https://sc01.alicdn.com/kf/HTB1twKVN...pg_350x350.jpg - Bing


    I don't know if something like this could work. I didn't look at dimension's

    Linear Flat Needle Roller Bearings - Bing
    I have a 6x12 covel that ill look at tomorrow to see if it has those racks

    Linear motion bearings|Products by Type:Rolling Bearings|Products & Technology|NTN Global




    th.jpg


    216005_aaa_rgb_history.jpg

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    Wow those are great ideas. The link mllud sent looks like it has exactly what I need. I will call Tuesday and see if they can help me

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    Default can someone with a Covel measure the diameter of their rollers?

    Quote Originally Posted by RobbyWeeds View Post
    Wow those are great ideas. The link mllud sent looks like it has exactly what I need. I will call Tuesday and see if they can help me

    Hopefully someone has a Covel like this and can measure the diameter
    of the rollers precisely.

    Since the rollers run both on the flat and V-way, the diameter is critical,
    since a diameter error on the flat will change the front of the table by that error, but the error on the v-way will change the rear of the table by a
    different amount which Pythagoras can clarify exactly.

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    ...:: Welcome to Triveni Needles Pvt. Ltd. ::...flat-roller-cages.jpg

    I had this link earlier but lost it. I cant tell if that v shaped one is made to work in a v way.

    google- linear flat needle bearings

    Ill check my covel tomorrow .

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    20190902_074912-2706-.jpg20190902_075019-2707-.jpg20190902_074855-2705-2-.jpg


    My old Covel 6x12 does not have those rollers. I lifted the table this morning. I hope you find something.
    A cant even find a model number on mine. Its much older.

    By the way Jim Christie's attached thumbnail reminded me of where to find those other bearings. Rang the bell.
    You will get it going again. Be sure and read Brandenbergers post.

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    Im thinking that one could insert same size shims in two places on the V way and two on the flat way. Perhaps try 1/2 in the front and 3/8 in the back and use something soft and wide enough so not to harm the machine ways..
    Then check to the the table is flat front to rear ..and the the clearance is good long travel table to saddle..would give indication if that size tall/good or short to the machines needs..
    *Yes best would be someone knowing the correct roller size.

    1/2" drill rod runs +- .0005 or so, A centerless shop or Dedtru on a surface grinder can quickly grind a set or rollers to .0002..Thinking one could make a roller rack set for less than $600. Just drilled through and pins installed would be fine.

    Although I think a drill rod piece would likely run very true end to end for that one piece..perhaps a Pm guy buying drill rod could measure a rod and see how close that rod runs end to end.
    I think Clausing /atlas press owns the rights to Covel now.

    Still the machine (likely) is worth adding the 600 fix.


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