Hobbymat milling machine

Hello to all

I have just brought a hobbymat mill and am looking for any information on maintaining it. I have looked in the normal internet places and found very little. I have the owners manual and the sales brochure but they give no help as to things such as headstock greasing and how to do it. The mill runs well and all the speed work Ok but i'm not sure when they were last lubed. any information would be a great help

Hi Adam

I believe it is best to use a slideway oil on all of the slides on your milling machine, grease for the spindle bearings if they are not the sealed type.

Emco

Thanks Emgee

Regular oiling I'm up to speed with It's more the mechanical side of the gear head I'm looking for. Like how to get into it

Hi Adam, the lubricant should be replenished or renewed every 1500 operating hours, but they advise this to be done at a service shop. If you wish to inspect the inside, then you should only remove the left gear cover. If you do not know when it was last serviced, then the best thing to do is have it serviced anyway.

Regards Nick.

Does anyone know why you should not remove the right cover. Before I had been told better I had them both off and as far as I know no harm was done.

My mill had not been used for some years so I scraped out as much of the old grease as I could and replaced with Molyslip. I do not know if this was correct but it is still working.

Thanks for the info. the mill is 25 years old so I was told so I think it would be a good idea to renew the grease in the head stock. If I remove the left hand cover only will that give me enough access to do the job? and do I remove the gear selector leavers first Thanks in advance for all your help

Adam

Hi Adam, sorry! I don't have that information, maybe someone else may be able to tell you.

Regards Nick.

Ah, the Hobbymat BFE, I had one around 20 years ago, really nice machines and very well made.

I had the head on mine apart, and cannot recall why only the left side cover should be removed for greasing, but I think it does give adequate access for greasing the internals.

I took the whole thing apart, including both side covers, to carry out internal repairs on a couple of areas that can give a bit of trouble if someone has been a bit rough and heavy handed when using the machine or changing the speeds.

The rather elaborate looking four speed constant mesh helical gearbox uses steel gears meshing with Tufnol gears, but I think later ones may have used Delrin or a similar material in place of the Tufnol gears. The verticle shafts in the gearbox have ball race bearings at each end.

Mine had Tufnol gears, and this laminated material seems fine for the gear teeth, but the small shallow drive dogs are also machined onto the side of these gears. So the layers that form them are inline with the shearing loads applied to them when cutting metal.

On the machine I bought I found a few of the drive dogs had sheared off, I think there are six on each gear so they will still keep running if you loose a few. It may have been a result of a previous owner over doing it a bit. So it is probably not a good idea to use a large diameter single point cutter, on a slightly heavy interrupted cut.

The Tufnol gears have a metal centre bush, and the other problem that can occur, as on mine, is these gears being pushed slightly off their bushes. This is caused if someone is impatient and heavy handed when using the levers to change gear, without carefully rotating the spindle back and forth to allow things to line up and click into place.

The column sits tightly in the split base casting, with three cap head screws. Only the two outer screws clamp the casting to the column, the centre screw opens up the casting to allow the column to be withdrawn. If you ever need to remove the column from the base, first slacken and back off the two outer screws, then screw in the middle one until it tightens and slightly opens up the casting to release the grip on the column. When the column is replaced, slacken and back off the centre screw before tightening the two outer screws.

I mention this because I have seen quite a few old Hobbymats with badly battered and bruised base casting, caused by wedges or big screw drivers being forced into the split casting in an attempt to force it apart to get the column out. It just isn't obvious what the centre screw is really for.

The original milling table for these is also very well made. A thick iron casting with three tee slots, plus a tee slot on the front face for the travel stops. Essel Engineering did offer some Taiwanese made milling tables for the Hobbymat mill head. These had just two larger tee slots on top, but were much thinner castings which left no room for the front tee slot and table stops. They are not a patch on the genuine table.

The mill head is a thick alluminium casting, but in the bottom they have an elaborately made thick walled cast iron liner. This liner is bored and honed to fine limits to take the very close fitting sliding quill.

I seem to remember later Hobbymats lost the geared head and resorted to belt and pulleys instead, to reduce noise I think it was suggested. But really to reduce costs on what must have been a relatively expensive to produce geared head.

So all in all a fine machine, which usually only gives trouble if abused.

Edited By Lathejack on 09/05/2017 03:50:17

Edited By Lathejack on 09/05/2017 04:01:29

Edited By Lathejack on 09/05/2017 04:07:37

Hi Lathejack

I agree with your view its a fine machine and thanks for all your information. I have now down loaded the technical specifications manual from the yarhoo Prazi group forum and I hope this will give me all the information I knead to grease the milling head

Thank you all for your help

Lathejack - thanks for the tip about the column clamping screws. I wish I had known that then!

I find that the head nods forward if the two clamping levers are loose - particularly the top one. I have often thought about fitting some sort of "gib" adjuster but never actually tried it. Do others have this problem?

Hi Roger

Yes my head stock leans forward so now I have another thing to get used to. I have a full set of metric collets that came with the mill but would like some imperial ones so I can use some of my existing tooling. Does any one know if they are a standard model or specific to hobbymat. I see they were listed in the original catalogue

Sorry to ressurect an old thread.

I've just bought a second hand 'Prazi_BF400' which is the same machine as the BFE65.

I have the same issue, the drive runs OK with the gear shifters in the lower position, but the gears won't engage at all if the speed change levers are rotated to the upper position.

The gears appear to be all lined up correctly with their meshing counterparts.

I'm stumped now...

Edited By JasonB on 16/07/2023 13:00:58

I am not sure what the problem is. I imagine you know to only change the speed when the motor is stopped.

If the problem is that the levers will not click into position, rotate the chuck by hand while trying the levers.

If the levers do click into position but there is no drive to the chuck you may have a more serious problem. It is a long time since I had mine apart but I think the levers operate dog clutches to engage the right gears. It is possible someone has tried to change gear with the motor running and damaged the clutches which in mine I think are made of paxolin or similar. The left cover can be removed to see what is going on.

The gears stay where they are, it's the face-dogs between them that move up and down and engage or disengage the drive - watching these whilst you operate the levers should give you a clue - have the dogs broken / worn off?

Sometimes the number of manual spindle rotations that have to be made before the dogs will align / engage are greater than one might expect.

Check that the selector levers are engaged correctly with the actuating mechanism.

Hello

Thanks for the posts.

I found a thread on here:

Hobbymat thread

Which mentions:

"The Tufnol gears have a metal centre bush, and the other problem that can occur, as on mine, is these gears being pushed slightly off their bushes. This is caused if someone is impatient and heavy handed when using the levers to change gear, without carefully rotating the spindle back and forth to allow things to line up and click into place."

I removed the left side cover - all seemed well, (lots of grease on the gears), and the drive dogs seemed intact on the Tufnol gears. Manually lifting the gear change forks engaged the gear change correctly, just the levers don't provide enough 'lift' for engagment.

Bearing in mind the thread mentioned above, I carefully put a flat blade between the upper gears and quite easily nudged the gears down on their bushes, maybe around 2mm.

With that done, full fuctionality has been restored. I suspect that the previous owner(s) had been changing gear with the motor running. Hopefully this won't happen again with carefull treatment.

Thanks again for the posts.