New Toy s/h RF45 Mill

SnakeyJ

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I had been looking for a small mill for the last few months and managed to find a (not so small) bargain on ebay the other day. I had been considering a VMC or an older universal mill (Elliott Omnimill), but this one came along at a silly price and will be a lot more manageable in my 8'x8' workshop.

The Chester Lux is a re-badged Chinese import RF45 clone, gear head mill with 2HP motor and R8 spindle, like the Grizzly0761, with a respectable 22"x7.5" travel and 13.75" travel on the Z axis. I'm guessing it's 8 years old, but pretty much unused and apart from a little surface rust the table looks unmarked. It will need a good clean and only came with a 4 and 5" swivel vice, a couple of threaded end mills and a 3" R8 HSS facemill. A full 320kg or 714lbs of chinese cast iron, but the head and column separated easily for and made it a comfortable two person lift to load up for the return journey. Not too bad for under £ 250 (USD325) and £ 100 travel expenses.

I'll post some more pics once I get it into the workshop and cleaned up.
 

Cadillac STS

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Very nice.

Scotch Brite pad and WD40 will take all that rust off and it will look nice again.
 

Tim9

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That's a great deal. I picked up one about 2 years ago. I had to rebuild the motor to get it up and running. And the gear drive is a little messed up on my mill. I can see where someone had it apart and it feels like the detent springs are not strong enough so it sometimes pops out of gear.
That said... I really like the RF45 clone mill. It has served me well and I'm able to easily work around the hookey speed detent issue. Anyway...I'd seriously consider buying a new one if this gives out on me. Its a good design IMO for a hobby machinist. Very capable IMO.
You did real good !!
 

FOMOGO

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Congrats on your the mill purchase. Pretty hard to beat the price, and while not a lot of tooling, at least enough to get you started. Half the fun of this hobby is acquiring or making all the things you need to make your machines capable of doing what you want them to do. Cheers, Mike
 

SnakeyJ

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Cheers guys, I had to clear the workshop and build a bench, but managed to slide this in to the workshop yesterday. I was doing it singlehanded, so a good excuse to strip, clean and lubricate all three axis and clean up the table.

I gave myself a bit of a scare draining the headstock oil - looks original and full of grit/sand. The motor runs fine, but gear box is seized :-(. Just ordered a set of NSK bearings and new seals, so will strip, paint and rebuild this with my 12 year old lad (school holidays here). Puts another £100 on the price, but will be good to know all is right.

More pics to follow.....
 

SnakeyJ

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Oh dear me, or as my son said OMG! I think this was very overdue and badly needed an oil change.......

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The shaft at the rear of the last image is the power shaft from the motor and the top bearing in this has seized almost solid (I can rock it a little with force, but it appears to have rusted solid).

The gear head is full of thick sludge, which is very sandy/gritty in the corners and almost like a congealed jelly over most of the insides - guessing this might be part microbial growth? On the last image the big cog is covered in rust flakes, though these scrape off and there does not seem to be any pitting on the gear itself.

Hopefully the new bearings will arrive by Tuesday, which leaves tonight and tomorrow for cleaning this all up.
 

PHPaul

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Even with the work needed, I'd say you did well. Upside is, when you get done tuning it up you'll know exactly what you have.
 

darkzero

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Oh dear me, or as my son said OMG! I think this was very overdue and badly needed an oil change.......

View attachment 287968View attachment 287967View attachment 287966

The shaft at the rear of the last image is the power shaft from the motor and the top bearing in this has seized almost solid (I can rock it a little with force, but it appears to have rusted solid).

The gear head is full of thick sludge, which is very sandy/gritty in the corners and almost like a congealed jelly over most of the insides - guessing this might be part microbial growth? On the last image the big cog is covered in rust flakes, though these scrape off and there does not seem to be any pitting on the gear itself.

Hopefully the new bearings will arrive by Tuesday, which leaves tonight and tomorrow for cleaning this all up.
While you're in there, might as well replace these 2 seals as well as the one for the motor shaft since you're replacing that bearing. The ones circled (2 stacked on top each other) prevents oil leaking onto the spindle/quill. I just had to replace mine last month.

287971
 

darkzero

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Not that you'll probably need them since you've got your head open but here are some pics for reference.

Turns out my motor shaft seal was already damaged but it never leaked from there.

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SnakeyJ

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Not that you'll probably need them since you've got your head open but here are some pics for reference.

Turns out my motor shaft seal was already damaged but it never leaked from there.
No thanks, those pics are really helpful - I hope I managed to order the correct oil seals.
 

SnakeyJ

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While you're in there, might as well replace these 2 seals as well as the one for the motor shaft since you're replacing that bearing. The ones circled (2 stacked on top each other) prevents oil leaking onto the spindle/quill. I just had to replace mine last month.

View attachment 287971
Thanks Darkzero - I think I have ordered replacements for these seals (35x45x10mm Nitrile Rubber seals). I ordered the following bits to replace all seals and bearings (including the two motor bearings as there is an annoying squeak from one):

2 x NSK 6205ZZ Metal Shielded Deep Groove Ball Bearing 25x52x15mm (6205ZZ-NSK) = £11.68
3 x NSK 6003ZZ Metal Shielded Deep Groove Ball Bearing 17x35x10mm (6003ZZ-NSK) = £12.57
3 x NSK 6007ZZ Metal Shielded Deep Groove Ball Bearing 35x62x14mm (6007ZZ-NSK) = £24.27
1 x Timken 30206 Metric Taper Roller Bearing 30x62x17.3mm (30206-TIM) = £13.19
1 x Timken 30207 Metric Taper Roller Bearing 35x72x18.3mm (30207-TIM) = £16.45
2 x NSK 6202ZZ Metal Shielded Deep Groove Ball Bearing 15x35x11mm (6202ZZ-NSK) = £7.58
2 x 35x45x10mm Nitrile Rubber Rotary Shaft Oil Seal R23 / TC Style (35x45x10_TC) = £6.24
1 x 75x90x8mm Nitrile Rubber Rotary Shaft Oil Seal with Garter Spring R23 / TC (75x90x8_TC) = £6.67

Not certain about the last item (seal for the end of the quill - I couldn't find a 75x90x6mm seal to match the Grizzly specified part - so this one is brought on spec to see if it might fit, otherwise I will reuse the original that looks ok. I think this seal is really a dirt/dust seal and not as critical as the gear box oil seals.

No doubt that the Timken and NSK bearings will be a good investment and should last a lot longer than the originals.
 

darkzero

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Not certain about the last item (seal for the end of the quill - I couldn't find a 75x90x6mm seal to match the Grizzly specified part - so this one is brought on spec to see if it might fit, otherwise I will reuse the original that looks ok. I think this seal is really a dirt/dust seal and not as critical as the gear box oil seals.
Sounds like your mill will be running tip top when you are done!

Not sure about that seal. I've never taken my quill apart yet so I have no idea. I've only taken the bottom cap off & I dont remember seeing a seal there on mine, just a bearing. But it's been a while since I've removed that cap & didn't look that closely in there.
 

SnakeyJ

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Head stripped and cleaned, in time for the new bearings which arrived this afternoon.

The original bearings were in a shocking state, two were seized and all show signs of internal rusting. The bearings are all marked ZDC, which appears to be decent manufacturer. Not sure if this is the result of fake bearings, casting sand or poor/original/unchanged lubrication - I would have thought even cheap hydraulic fluid would have some rust inhibitors.

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Anyway, all's cleaned and ready to rebuild, and pending a new oil sight glass and some ISO68 fluid, I should have this back up and running tomorrow.

I will run it up and through the gears for 6+ hours, and then dump/change the oil again - just to flush any crud that's still lurking between the gear teeth.
 

SnakeyJ

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Dumbass question - all the removed bearings from the gear box had both shields left on, but as this is an oil filled gear box is it not normal to remove the internal facing shields to allow the oil/hydraulic fluid to circulate?
 

mikey

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Oil will easily get into a shielded bearing. The shield is there to prevent entry of debris into the bearing. Shielded bearings are lubed with oil, while sealed bearings are lubed with grease by the factory.
 

markba633csi

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It looks as though the machine was used a few times; the owner suddenly de-materialized, then it sat for ages, in an unheated environment
You'll have a nice unit when you get it back together
Mark
 

Tim9

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I think I read a few articles about the poor quality oil used in these mills along with the excess gritty substance left in the gearbox. It"s recommended to drain and flush them when you get the mill and refill with a quality lubricant. Plus get any sand out in the process. My mill had that same discolored oil in it. You could tell by the clouded sight glass.
Yours looks worse than many pictures I've seen. But it'll be fine once you finished the rebuild IMO.
 

SnakeyJ

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I think I read a few articles about the poor quality oil used in these mills along with the excess gritty substance left in the gearbox. It"s recommended to drain and flush them when you get the mill and refill with a quality lubricant. Plus get any sand out in the process. My mill had that same discolored oil in it. You could tell by the clouded sight glass.
Yours looks worse than many pictures I've seen. But it'll be fine once you finished the rebuild IMO.
Thanks Tim - reassuring and useful advice for anyone buying or sitting on one of these mills - much appreciated
 

SnakeyJ

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It looks as though the machine was used a few times; the owner suddenly de-materialized, then it sat for ages, in an unheated environment
Thanks Mark - I think you're spot on in this assessment, I didn't meet the owner in person but he was described to me and it certainly looks like he brought the mill, mounted a 4" vice and only did a little drilling (judging by the clean spot underneath the vice had never been moved).

Oil will easily get into a shielded bearing. The shield is there to prevent entry of debris into the bearing. Shielded bearings are lubed with oil, while sealed bearings are lubed with grease by the factory.
Cheers Mike - all of these were listed as shielded and pre-greased, so should let sufficient lube in and help keep any big contaminants out. The manufacturers blurb on the website was a little vague:

Metal Shielded Deep Groove Ball Bearings: One of the most commonly used bearings, these types are manufactured with metal shields inserted into the outer raceway, these fit in closely to the inner race providing protection against light mechanical damage, some protection against the ingress of moisture, dust and other foreign matter and serve to retain the pre-filled grease in the bearing.
Shields can be removed for applications that only require 1 shield
Benefits: Provides light mechanical protection, limits moisture and dirt ingress, lubricated for life, cost effective solution
 

mikey

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Sorry, I was leaving the house when I wrote what I wrote and I should have specified an oil bath. Let me explain.

A friend had an old lathe, I think it was a Clausing but I'm not sure. It had shielded bearings in the gearbox and he wanted to change them to sealed bearings. I didn't see why he couldn't and encouraged him to switch them but he queried SKF about it first. These bearings apparently live in an oil bath that gets hot and the concern he had was that this would thin the grease in a sealed bearing and reduce bearing life. SKF agreed with him for this application - low speed, oil bath, heat. I learned something that day and was glad he didn't listen to me. SKF also mentioned that oil baths in lathes can get hot and when they cool, water can condense - never thought of that one before. Water = rust, so they recommended he change oil on a regular basis (annually).

Ran home and opened up the gear box on my Emco lathe and found open FAG bearings - no shields, no seals - but no rust because I'm anal about gear oil changes annually.

Apparently, there is a great deal of controversy about which bearings to use in a gear box. Some guys use sealed, some shielded and some use open bearings. I don't know who is right but I do know I was wrong on this occasion.
 

mikey

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Another time I was wrong about bearings. When I changed the spindle bearings in my RF-31, I went from open tapered roller bearings that were greased to angular contact bearings that were sealed both sides. Everyone knows you have to run in new spindle bearings, right? I thought so anyway, but queried FAG just to be sure. Turns out that their precision sealed bearings don't require any break in at all. Wrong twice. Now I contact the maker anytime I contemplate a bearing change from the original spec because conventional practices that I thought I knew have exceptions.
 

SnakeyJ

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Another time I was wrong about bearings. When I changed the spindle bearings in my RF-31, I went from open tapered roller bearings that were greased to angular contact bearings that were sealed both sides. Everyone knows you have to run in new spindle bearings, right? I thought so anyway, but queried FAG just to be sure. Turns out that their precision sealed bearings don't require any break in at all. Wrong twice. Now I contact the maker anytime I contemplate a bearing change from the original spec because conventional practices that I thought I knew have exceptions.
Mikey, please excuse my delayed response but had a busy couple of days - many thanks for your input and candour here. I make plenty of mistakes, but avoiding repetition is definitely the key to wisdom :)
 

SnakeyJ

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All up and running - and looking pretty good. I do get a little intermittent noise from the motor, which has a plastic press on cooling fan with a split hub - It turns with the motor and keeps it cool, but needs to be replaced before it finally gives up.

I also broke the oil sight glass on reassembly - I purchased a new M18x1.75 sight glass (as per the grizzly manual/spec), but on arrival this was much smaller than the old one (27mm thread diameter). Temporarily bodged with a stainless steel washer/reducer and plenty of RTV silicone and new one on order.

Other than this all sounds and looks good. The gear changes are a little hit and miss and bear only a vague relationship to the marked positions on the front plate. It needs a little work to ensure the gears are properly engaged and avoid crunching, but once in gear it stays put and runs very well.

I've done a little test milling on a scrap piece of 3/4" ms bar and quite pleased with removal rates and finish (not a great picture), but squared off with a 3" HSS facemill and then the corners shamfered off with 5/8" endmill (the rough turned ends are from old lathe alignment)

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Now spent a small fortune on Vertex Clarkson type holders, endmills, clamping kit, edge finder and 3 axis dro kit (incoming).

First project will be brackets for mounting up the DRO, and then a small permanent magnet alternator as part of a school science project with my son.
 

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The bearings in the top cover should be sealed as they aren't in an oil bath and don't get a splash feed. I have some very high spec synthetic grease I was given, low viscosity, so I popped the seals and re-greased with the good stuff,(not saying what was original is not good). A bit of fettling and these mills give great service. Leadscrew nuts are the weak point but as CNC conversions have been done to so many ballscrews are available if they war out.
 

SnakeyJ

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Thanks - I will keep a close eye on these bearings and not to painful to access to check, relube or replace if needed.

Point taken on the lead screw nuts, but actually X and y move very well with little back lash. However, the Z access is horrendous and will need some attention in the near future!
 
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